I was going to guess Merced or Manteca. I haven't been to Modesto in a long time. But we had a family reunion in Santa Cruz last June. This year I may go back to Gilroy for my high school reunion. We're looking into SoCal for a family vacation next summer. I kind of miss living there, but it has changed a lot since I was a kid. Too many people and it's too expensive.
You are lucky to go so long! When we were there last year, between Thanksgiving and Christmas break seems to be the perfect time to go to the parks and on the cruise. It was warm, not hot, and the parks weren't too crowded. If my mother-in-law hadn't been in an electric scooter

, we could have walked on about half the rides without waiting. My wife uninvited her to go with us to the parks this time

.