Depending on the ages of your children, the time of year and your travel route, you might consider
There is the Monterey Bay Aquarium in Monterey California, not a theme park but it is a fabulous aquarium.
Gilroy Gardens (formerly Bonfante Gardens) in Gilroy, CA along Hwy 101
www.gilroygardens.org
This theme park celebrates gardens and the farm products grown in the local area. Rides are for younger (under 12) children, mostly. Stunning gardens to walk in or take the boat through. Lots of education opportunities and some entertaining shows.
Also, if you have older kids, there is Great America in Santa Clara, CA
http://www.pgathrills.com
There are a lot of attractions, landmarks, tourist spots, etc. all through California.
Have a great trip (or if I answered this too late, I hope you had a great trip already)