Here is a brief description of the 5 parks as well as directions by car and public transportation. Please consult the parks' individual sites for more information.
A. DISNEYLAND RESORT (disneyland.com)
To purchase tickets to the parks with or without hotel or air, click on the appropriate circle under "plan your stay" in the center of the disneyland.com page. By buying either a 3-day, 4-day, or 5-day 'Park Hopper' ticket, you will be allowed admission to both Disneyland Park and Disney's California Adventure.  Downtown Disney is always free to enter (no admission charge).
The resort consists of three locations in Anaheim, California:
a. Disneyland Park -- the original amusement park. Visit Mickey and the Gang at Disneyland
b. Disney California Adventure --  Shows, parades and attractions celebrating California's storied past and exciting future. From the gold rush to Hollywood's golden era to the timeless allure of the beach, discover the vast and diverse Golden State.
c. Downtown Disney -- Restaurant, shopping and entertainment complex along the lines of Universal CityWalk
If you have questions about local hotel accommodations or operating practices at Disneyland, it is recommended that you post your question on the TripAdvisor Forum for Anaheim. Their direct link is: http://www.tripadvisor.com/ShowForum-...
DIRECTIONS to the Disneyland Resort -- By Car (check the disneyland website for more details):
Take I-5 (Interstate 5) south. Exit Disneyland Drive and turn left (South). Then...
for... Disney California Adventure™ and Disneyland®:
Proceed across Ball Road. Use the left three lanes to access the Mickey & Friends Parking Structure.
for ... Downtown Disney® District:
Continue on Disneyland Drive, staying in the far two right lanes. Follow the signs to the most convenient parking area.
for ...Disneyland® Hotel:
Continue on Disneyland Drive, staying in the far two right lanes. Turn right (West) on Magic Way and follow the sign to the hotel entrance on the left.
for... Disney's Grand Californian Hotel®:
Continue on Disneyland Drive, staying in the far two right lanes past the Disneyland® Hotel. The hotel entrance is located on the left at the second traffic signal.
for... Disney's Paradise Pier® Hotel:
Continue on Disneyland Drive, staying in the far two right lanes past the Disneyland® Hotel. The hotel entrance is located on the right at the second traffic signal.
DIRECTIONS to the Disneyland Resort -- By Public Transportation...
... from LOS ANGELES INTERNATIONAL AIRPORT (LAX):
They are three major transfer agents between LAX and the Disneyland area as well as a number of smaller services.
The three larger transfer services are:
1. The Disneyland Resort Express Bus ( http://www.graylineanaheim.com/airpor... )
This is a large coach bus which departs from each terminal of LAX every 30 minutes during most of the day (every hour at other times).  The coach is designed for arriving and departing passengers at LAX so there is luggage storage aboard the bus.  After stopping at all of the airport terminals, the bus goes initially to the hotels on the Disneyland resort grounds: the Disneyland Hotel, Disney Paradise Pier and Disney's Grand Californian Hotel.  Passengers should ask the coach driver for advise on which hotel at which to exit the bus and for walking directions to the Disneyland entrance gates. 
The following are transfer services that offer vans (shared or private) and sedan cars (with drivers).  They pick up at LAX 'as needed' (you may make a reservation or simply wait at their assigned pickup areas and the next van will pick you up.  Sedans and Private Vans must be reserved in advance).  "Shared' vans can circle the airport to pick up passengers, stopping at each terminal twice (two complete circles of the airport are permitted but happen infrequently).  'Private Vans' and sedans go directly to Disneyland.  Here are the two companies that provide these services from their fleet of dozens of vehicles that are stationed at LAX when they are not 'on the road':
2. Super Shuttle (supershuttle.com)
3. Prime Time Shuttle (redvans.com)
Other, smaller, independent companies provide 'shared van' and/or 'private van' services which must be reserved in advance.  The van that you ride does not enter the airport until you contact the service to indicate that you are waiting in front of the terminal.  The driver is not permitted to enter the airport until all of the passengers for his/her PRE-RESERVED van are waiting in front of their terminal. 
The big advantage to the 'big 3' is that if a driver becomes ill, is in a traffic accident or is just late in arriving, the company has the manpower to send in one of the backup drivers.  If a smaller, independent driver meets some unfortunate fate, the passenger is out of luck.  Of course, this doesn't happen very often. The advantage to the smaller, independent companies is that they may offer a better price and their service might be better since the Big 3 services can get crowded with passengers. 
Here is a list of smaller, independent transfer services:
1. Zippy Shuttle (http://zippyshuttle.net/rates.shtml) -- Rate from LAX to Disneyland (Anaheim/Garden Grove area) as of 1/10/11 is
$85 total for the first three passengers plus $5 for each additional passenger.
2. Karmel Shuttle Service, Inc (714) 670-3480 (toll free in the U.S.: 888-995-7433 http://www.karmel.com/shuttle/ (email for travelers who don't wish to call: info@karmel.com).  Conact Karmel for rates.
...from DOWNTOWN LOS ANGELES (UNION STATION AND PERSHING SQUARE) there are three options; a train bus comination from Union Station, a shuttle/limo service or the metro bus.  
If you are staying outside of downtown Los Angeles, you must either travel into downtown first or you may travel to LAX to pick up the airport bus from LAX to Disneyland as described above.
If you wish to depart for Disneyland from Union Station (downtown Los Angeles), take the "red line", "purple line" or "gold line" metro train to Union Station. (The Red Line runs through North Hollywood, Universal City and Hollywood; the Purple Line runs through Koreatown and Mid Wilshire; the Gold Line runs from Pasadena into downtown and then out to East Los Angeles. You may also connect to the 'red line' from the "blue line" metro rail line that run from Long Beach into downtown Los Angeles. If your hotel is in Santa Monica, Beverly hIlls or elsewhere, take a bus to Union Station. (For bus information, go to mta.net. In the right column of the screen, under metro planner, type your hotel's address such as "3332 Wilshire Blvd" (but omit the quotation marks (or type in the closest intersection like "Main street / 23rd Avenue" (but omit the quotation marks but include the slash if you are specifying an intersection). Next to the word "TO" type Union Station. If you are taking at least 4 bus or metro rail trips in one day, buy a "day pass" for $7 (plus the one-time cost of a TAP CARD on which to load the fare -- $1) rather than individual tickets for $1.75.  NOTE: if you travel on two different metro lines (for example, the 'blue line' and then connect to the "red line") that is considered two different trips and requires that you purchase TWO DIFFERENT TICKETS. There are NO FREE TRANSFERS between metro RAIL lines. Instead, buy a $7 'day pass' and you can ride unlimitedly on the metro trains and the Metro buses.  There is one exception to the 'no free transfer' restriction.  If you use a TAP CARD to pay the single-ride fare on a metro rail train or bus ($1.75), you may transfer to other Metro buses or trains at no extra charge as long as the entire transfer is no longer than 2 hours and you do not reverse direction.
ONCE YOU ARRIVE AT UNION STATION, take either a Metrolink Train (metrolinktrains.com) or an Amtrak Train (amtrak.com) to either Fullerton or Anaheim station. Both trains run on the same tracks and stop at the same stations. (Note: The Metrolink is an aboveground commuter train line that is not related to the 'metro rail' below-ground metro lines). Metrolink trains might be a little less expensive depending on the number of children in your party. Also, MOST IMPORTANTLY, Metrolink runs VERY FEW trains compared to Amtrak, so if there are no metrolink trains on the day and time you wish to travel, take an AMTRAK train. You may not purchase tickets for metrolink in advance online. You MAY purchase Amtrak train tickets in advance online. Trains take approximately 37 minutes to get to Fullerton and 42 minutes to get to Anaheim. Even though Disneyland is in Anaheim, in most cases it is better to take the train to Fullerton (rather than Anaheim) since the bus connections are better at Fullerton. There are exceptions to this rule as follows:
1. If you plan on taking a taxi to Disneyland from the train (rail) station, the fare to Disneyland from either the Fullerton or Anaheim ARTIC station are the same but you will get to the park faster using the Fullerton Station.
2. If you are planning to arrive at Disneyland by NO LATER than 9 o'clock in the morning, there are special EXPRESS BUSES (Route #430) that will take you from Anaheim Station to Disneyland ($2 / a 12 minute ride). These buses depart Anaheim rail station and head for Disneyland at 6:31, 7:01, 7:23, 7:52, 8:31, and 8:45. In the afternoon/evening, the buses depart from Disneyland and return to the Anaheim Rail Station at 3:48, 4:19, 4:56, 5:15 and 6:01. The fare is, again, $2 and the ride (a slightly different route) takes 14 minutes.
If you plan to arrive at Disneyland after 9 am or depart Disneyland before 3:48 or after 6:01, you should use the Fullerton Rail Station since coming into the Anaheim rail station during those times will necessitate taking 2 separate buses (the #50 Westbound from Katella-Douglass to Katella-Harbor followed by the #43 Northbound from Katella-Harbor to DL. The ride will take 17 minutes.
If you arrive at Fullerton, here are the bus directions:
Take the Bravo Route 543 Express bus, runs seven days a week (starting February 8th, 2015), limited stops and a 20 minute ride. If the Bravo isn't running, take the #43 southbound (Same route, just more stops along the way), The buses depart from one of two locations: either the #1 Transit dock (Parking space #1 for the buses, adjacent to the rail station) or down the road to the west a short walk at the corner of Harbor Bl and Santa Fe Avenue (northwest corner), The buses alternate between these two starting points. The fare is $2 and the ride is 21 minutes.
For information about local buses for Disneyland, go to: www.octa.net and click on trip planner. Enter AMTRAK as the starting point and DISNEYLAND as the ending point. The system will ask you to clarify WHICH Amtrak station you want (click on either FULLERTON or ANAHEIM. The system assumes ANAHEIM unless you change it).
Total travel time from Union Station: 1 hour and 7 minutes, the cost of the train is based on the day of the week, and what type of ticket you purchase. For example, the fare for four adults on Amtrax to Fullerton on a Monday mid morning in June 2014 was $96 return and the service ran less than hourly. I would check the websites for the pricing for your specific day. (Both trains systems do offer discounts for youths).
...from Pershing Square in downtown Los Angeles:
Pershing Square is served by the purple and red lines, and if travelling from out of town exit to Pershing Square and find the bus stop for route 460 to Disneyland. It is on the north side of the square, with the metro station to your left when standing at the bus stop. For $2.90 single (metro day passes are valid but there is a small supplement on this route), you have a 2 hour bus journey through south LA direct to the entrance to Disneyland. Buses run typically 2 or 3 times an hour and drop and pick up right outside Disneyland. The service is popular with workers so runs from Downtown from very early morning with the last arrival back in town at approximately 2.00am.
(Hotel + Universal Studios packages are at www.univacations.com/index.asp)
At the above site, be sure to look under Universal Studios HOLLYWOOD for the Featured Deal for Universal Studios Hollywood (Do not click on Universal Studios, ORLANDO, FLORIDA, by mistake).
DIRECTIONS to Universal Studios Hollywood -- By Car (check the Universal website for more details):
Take the Hollywood (101) Freeway north from downtown or Hollywood to either the Lankershim Blvd. or Universal Studios exits. Follow the signs to the parking lots.
DIRECTIONS to the Universal Studios Hollywood -- By public transportation:
Take the 'red line' metro to Universal City. Cross the pedestrian plaza, then cross Lankershim Blvd. and wait at the bus stop on the right side of the road for the free shuttle up the hill to Universal Studios. Alternatively, you can walk up the hill (about a 10-12 minute walk). If your hotel is not near the 'red line' metro, get bus and metro rail info at mta.net. In the right column of the screen, under metro planner, type your hotel's address such as "3332 Wilshire Blvd" (but omit the quotation marks (or type in the closest intersection like "Main street / 23rd Avenue" (but omit the quotation marks but include the slash if you are specifying an intersection). Next to the word "TO" type Universal Studios. If you are taking at least 3 bus or metro rail trips in one day, buy a "day pass" for $7 rather than individual tickets for $1.75. NOTE: if you travel on two different metro lines (for example, the 'blue line' and then connect to the "red line") that is considered two different trips and requires that you purchase TWO DIFFERENT TICKETS. There are NO FREE TRANSFERS between metrorail lines. Instead, buy a $7 'day pass' and you can ride unlimitedly on the metrorail trains and the buses. There is one exception to the 'no free transfer' restriction.  If you use a TAP CARD to pay the single-ride fare on a metro rail train or bus ($1.75), you may transfer to other Metro buses or trains at no extra charge as long as the entire transfer is no longer than 2 hours and you do not reverse direction.
Warning, individual tickets for $1.75 expire 2 hours after purchase. If you plan to use individual tickets for each direction of your trip, do not purchase the return tickets until you are ready to board the train for the return trip.
C. Six Flags Magic Mountain (Theme Park) and adjacent Six Flags Hurricane Harbor (Water Park).
NOTE: Hurricane Harbor is only open May through September.
Six Flags Magic Mountain is known as the Roller Coaster Capital of the World, with more Roller Coasters than any other park in the world.  It also has a few Kids areas, mainly themed to Bugs Bunny and their friends.
DIRECTIONS to Six Flags Magiic Mountain -- By Car (check the Six Flags website for more details):
Take the Hollywood (101) Freeway north to the 170 Freeway north. Take the 170 Freeway north to the Interstate 5 Freeway north (the 170 Freeway automatically ends at the I-5 north). Take Interstate 5 north to Magic Mountain Parkway. Exit Magic Mountain Parkway, turn left at the traffic signal at the bottom of the exit ramp going under the Freeway overpass. Proceed along Magic Mountain Parkway to Parking Toll Booths and entrance to Six Flags California.
DIRECTIONS to Magic Mountain -- By Public transportation (check the Magic Mountain website for more details):
Local public transit to Magic Mountain is limited.  There are 3 departure points in the L.A. from which one can reach Magic Mountain but they all involve transferring between 2 or more conveyances and call for less than a full day's visit to the Park.  Here are the departure points and the transit instructions:
a. From the west side of L.A. (this is perhaps the easiest, quickest and least expensive transfer):  NOTE: this routing is available on weekdays only (no Saturdays or Sundays):
i. From the NE corner of Wilshire Bl and Glendon Av just east of Westwood Village, take the Santa Clarita #792 bus [marked 'VALENCIA INDUSTRIAL CENTER'] heading west to the SE corner of McBean Parkway and Magic Mountain Pkwy.  Transfer there to the Santa Clarita #3 to Magic Mountain.  The return buses depart the Magic Mountain area before the Park closes for the day so one's day at the Park will be shortened a little by using this transfer method. Transfer time: 90 minutes, each way.  Check the 'trip planner' on Metro.Net for up to date schedules.
ii.From Hollywood, take the red line metro rail north to the North Hollywood Station (last station on the line).  Transfer to Santa Clarita #757 bus north on Lankershim Bl and get off at the Valenica Bl/McBean Transfer Station.  Transfer there to the Santa Clarita #7 bus to Magic Mountain.  Transfer time: 2 hours, each way.  This route is available 7 days a week. Check the 'trip planner' on Metro.Net for up to date schedules.
iii. From downtown L.A. --
On weekends, take the red line metro north to North Hollywood and follow the above transfer instructions from Hollywood. Check the 'trip planner' on Metro.Net for up to date schedules.
On weekdays,  take the Santa Clarita #794 bus from parking space #1 of the bus plaza behind Union (rail) station in downtown L.A. Get off at the SW corner of Valencia Bl & Rockwell Canyon. Transfer to the Santa Clarita #3 bus from the northwest corner to Magic Mountain.  Transfer time: 90 minutes. Check the 'trip planner' on Metro.Net for up to date schedules.
There is a coach tour that will pick you up at your hotel, drop you at Magic Mountain and pick you up at the end of the day and return you to your hotel. Go to http://www.starlinetours.com/los-ange... for more information. At the time of this printing, the cost was $90 and included admission to Magic Mountain (and, of course, you are spared the experience of driving and finding parking).
D. Knott's Berry Farm (www.knotts.com) includes the amusement park plus Soak City (which is the adjacent water park):
DIRECTIONS to the Knott's Berry Farm -- By Car
(For additional info, check the Knott's website under 'plan a visit', then 'theme park' then 'directions'. On the page with the map, click on 'directions to knotts' at the bottom of the page):
Directions: Proceed South on Interstate 5 from downtown Los Angeles. Exit at Beach Blvd. Turn right (south) onto Beach Blvd. Proceed five blocks until you reach Knott's.
DIRECTIONS to Knott's Berry Farm -- By Public Transportation
Your trip will commence from downtown Los Angeles at the northwest corner of Flower Street and 7th Street. (You may reach this intersection easily by taking either the 'red line' metrorail train or 'blue line' metrorail train to the 7th Street metro center station (where the two lines meet). If your hotel is not close to one of these metrorail lines, take a bus. Bus info is available by going to mta.net and specifying your hotel's address after the word 'from' in the right column of the main mta.net page. Next to the word "To" type the following: Flower Street / 7th Street (being sure to include the slash between the two streets). The website might ask you to verify this intersection by providing a list of intersections with similarly sounding names. Be sure to select the intersection with 90017 as its zip code.
Emerge from the 7th Street station and walk to the corner of 7th steet and flower street, take MTA bus #460 to Anaheim and get off at Knotts about an hour (or a little longer) later. (You may use mta.net to find a schedule of times for this bus route. Simply enter 7th street / flower street after the word 'from' and type in Knotts after the word "To").
Also, Metrolink Trains go from Union Station to Buena Park, where you would transfer to the OCTA Route 29 bus to the park.  The problem with the Metrolink Train is limited evening and weekend service.
ALTERNATIVE WAYS TO GET TO THESE PARKS
In additon to public buses, metrorail and trains, the major coach tour companies offer trips to Universal, Knott's, Six Flags and Disneyland that include door-to-door service from your hotel as well as the admission to the park. Go to starlinetours.com(click on the area that you will be departing from) or www.graylineanaheim.com