If you're up in NorCal, Trinity Center (O86) is pretty cool.
There's also Chico (CIC), you can go tour the Sierra Nevada Brewery.
There's Monterey (MRY), You got cannery row, the wharf & Aquarium
Down South...
There's Oceano (L52)
You can go rent quads & dune buggies. Restaurants with in walking distance. On-airport camping is available & there are showers at the RV park just across the bridge.
Frazier Lake Airpark (1C9) Just North of Hollister. Not much around, just a nice grass runway and a cool airport with a parallel water "runway" for sea planes.
Harris Ranch (3O8) is a good place to over night if camping is not your thing. I'd recommend Columbia (O22) but its on fire...
The Owens Valley is awesome, but there is nothing really quick or convenient next to any of the airports. And once you're there, thre really isn't a whole lot to do unless you have your fishing, hiking, shooting, etc... gear with you. And it's hot this time of year.
There's Bacon Strip Ranch,
http://www.baconstrip.net
If you like shooting & the desert its a great time. (Still hot)
The equivalent to Bacon Strip up in NorCal would be Gravely Valley (1Q5), another really cool place.
You can always check out Trona (L72) and see the city time forgot. I was there about a year ago and there was still no cell service, and barely TV.
For some good breakfast & lunch check out Woodlake (O24) it's just north of Porterville. It's a fun little airport and & good stop.
If you do camp and/or just need a cheap place to crash for the night check out Tehachapi (TSP) Fully stocked, air-conditioned pilot lounge with showers, TV, WiFi and Lazy Boys to sleep on. They have a really nice camp ground too stocked with fire wood, fire pits, lots of shade trees, AC power, green grass and picnic tables. There's also a really good BBQ joint called the Red House within walking distance, in town.
This was at TSP