Half Moon Bay has several restaurants just a short walk into Princeton By the Sea, off the south end of the runway. Mezza Luna, Half Moon Bay Brewing Company, and a crab shack among them.
Petaluma - the famous 29'er Diner.
Watsonville - the restaurant seems to change owners and themes fairly regularly, not sure what is there now. But it is usually good.
Livermore - the restaurant at the golf course
I've been less then impressed by the food at Nancy's at Willows, but the ambience is first-rate. Maybe I just ordered the wrong thing.
Auburn - already mentioned, really nice. Closes fairly early, like 2-ish.
Red Bluff has a nice cafe
Benton Field (Redding) has a nice cafe
Chico just a 5-minute walk east from the airport to a really yummy sandwich/burger place. Not your usual airport cafe, it is a lunch place for the light-industrial area crowd
Columbia - just a short walk into the old ghost town. Really good mexican restaurant. Also in the other direction out of the airport, a sandwich shop.
Added bonus - you can land on grass if you want. I always do.
+1 for Harris Ranch, but expect a wait.
As far as I know, the restaurant at Lampson has been closed for years. Also I thought the Hollister sandwich shop closed - maybe they re-opened?
Klamath Falls has a nice restaurant, but it seems to be closed often, then re-opens. Not sure of current status.