Disneyland in Anaheim (a suburb of Los Angeles) is an absolute must see experience in the Inland Empire, especially if you have small children. You may recognize many of the rides and attractions because you have seen them in Disney movies. There is something for everyone at Disneyland: rides, movies, fantastic buildings like the Disney castle, costumed Disney characters, a parade (or two) every day and hundreds of attractions that change all the time. Disneyland is surrounded by hotels and inns which make it easy to enjoy the Disneyland attractions without long commutes. You will definitely want a convenient place to collapse after a day or night at Disneyland.
Disneyland
1313 S. Harbor Blvd.
Anaheim, CA 92802
714-781-4000
wdwinfo.com
The Jet Propulsion Laboratory in Pasadena (another suburb of Los Angeles) was not designed as a kid's playground but it definitely is---especially for older kids. It is a NASA laboratory dedicated to the nonhuman exploration of space---the place where the Mars rovers are built. JPL is visitor friendly and if you call a few days in advance it is easy to set up a guided tour. Be sure to see the clean room where robotic space vehicles are built and the "Mars Yard" where Mars rovers are tested. There is a gift shop where you can buy one-of-a-kind memorabilia. If you are lucky enough to visit in the spring you might catch one of the visitor's days where all the laboratories put on special displays and everybody gets a free JPL hat.
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena CA, 91109
818-354-4321
jpl.nasa.gov/
If your kids like Legos then Legoland in Carlsbad, just north of Los Angeles, is a great place to spend an afternoon. There are rides, water slides, an aquarium and giant attractions made entirely of Logos. There are Lego towns and villages your child can walk through---like Godzilla walking through Tokyo. There is also a great Lego "Mindstorms" display if your kid is interested in robots. It is a truly amazing place for kids and adults alike with one drawback: when you get home your kid is going to want a lot more Legos.
Legoland
One Legoland Drive
Carlsbad, CA 92008
760-918-5346
sandiego.org/
Magic Mountain in Valencia (just north of Los Angeles) is the place to go if you are interested in rides. There more than 100 rides in the 260 acre park featuring 16 world class roller coasters. Famous attractions include the X2 "fourth dimension" roller coaster which is billed as the ultimate roller coaster experience and the SUPERMAN that goes more than 100 mph and 415 feet off the ground. There are also attractions such as concerts, restaurants and movies for the less adventurous members of your group.
Six Flags Magic Mountain
26101 Magic Mountain Parkway
Valencia, CA 91355
661-255-4100
sixflags.com/