There are a number of CGs from Big Sur to SF. Any state beach that you could actually get into would be great. Laguna Seca, Monterey Fairgrounds to the south. There is a small park just south of Half Moon Bay harbor. From there they tend to get more expensive. North of SF there are some lower cost parks and you could take the ferry into SF. Santa Cruz harbor has a small CG, probably expensive? The Sausalito Bay Model is an interesting visit - working model of the tides.
As a general guideline any CG near water is likely to be expensive and/or difficult to get a reservation.
