Just plugging one of my local parks here, if anyone's visiting the Bay Area for the holidays, I highly suggest checking out Bonfante Gardens Holiday Lights Celebration:

http://www.bonfantegardens.com/holidaylights.html

Already considered one of the the world's most beautiful family theme parks, becomes even more amazing this time of year with the park covered in thousands of lights and special holiday theming. Definitely worth checking out if you're in the area.