I have been to following airports and my kids loved it..
Following is my experience, not an expert advice, use your own discretion.
Halfmoon bay: walk out of airport and you are on beach, fish and chips.
Monterey flight academy: private, very close to beach, I couldn't land my twin engine there, but small plane should not be a problem.
Oceano: 3 minute walk to beach, ATV sand dune buggies, shops etc, (Challenges; marine layer no instrument approach, 2400 runway, SLO Wx forecast, may not tally may land santa maria )
Columbia: camping, walk to historic town, ice cream etc
Pine mountain lake: great location (my kids best choice (if you can get ground transport to lake (kayak, boat rental, swimming, food, other activities possible) during summer, Yosemite gate around 20 miles.
Truckee : may get shuttle bus to lake, restaurant on field, check wx, Consider density altitude and Icing, avoid flying around noon to avoid turbulence.
Carlsbad: 4 miles to LEGOLAND, beach, easy to get uber,
Fullerton: close to Disney land
Catalina island: 20 miles off coast (over water flight consideration), watch for down draft on approach to land, small landing fee, restaurant.