These are the best Theme parks in California.
But, don't visit them too often... you could spoil the fun ;)

Disneyland, California
• http://www.disneyland.com/
• http://www.disneyclub.com/

Six Flags, Magic Mountain
• http://www.sixflags.com/parks/magicmountain/
• How to have the best day at Magic Mountain?

Sea World Adventure Park
• http://seaworld.com/

Knott's Theme Park
• http://www.knotts.com/