First amusement park I have a memory of is probably Santa Cruz Beach Boardwalk, which I still head over to a few times a year. I don't ride the rides anymore, but usually to walk around and soak up the atmosphere and hear the free concerts on Friday nights in the summer time.
Although, I do remember Frontier Village in San Jose, which closed after Marriott's Great America opened in 1976. Sadly, Great America is a shell of its former self as it's has changed owners several times in 37 years. (wow 37 years!!!)