I agree with what everyone has said so far but...
Before you even consider going to Great America (I have a prejudice) go to Six Flags Discovery Kingdom (Between Napa and San Francisco).
SFDK is a very fun park because it has both amazing animal exhibits and fun coasters. There is Shouka the killer whale, all kinds of zoo animals such as elephants and tigers, and lots of dolphins! For an extra $5 you can actually get to feed and pet some of the dolphins (the seals too i think) and sometimes they have special picture opportunities with the animals. If you do go, ride Medusa – the floorless coaster– it's fun and not too scary.
I hope you have a great trip in California!