Ben nailed the big ones. Columbia also has a state park / gold mining town about 1/2 mile away. You can always get a sandwich, ice cream and sarsaparilla at the 'ole saloon... not that anyone knows what sarsaparilla is anymore.
Auburn (AUN) has a killer breakfast and lunch menu, and the restaurant patio couldn't be any closer to the ramp. Col "Bud" Anderson is a local there. I had breakfast with him a year ago just because I happened to be sitting next to him, and I was wearing a Cub hat.
Lodi is a fun approach. The restaurant has a good menu, but it's cash only. You can sit in the window and watch the skydivers.
Half Moon Bay is always popular. Eat there at the field, or better yet, taxi all the way south and you're a 100 yard walk from Mezza Luna (great Italian) or Half Moon Brewing. Watch the fog. It moves in quick.
Harris Ranch is popular for big hunks of beef. To get there, fly south on Hwy 5 with the window open until is smells really, really bad. Then land. Seriously. It reeks of cow. I guess that's a good thing...
Nancy's Airport Cafe at Willows has maybe the best pie in the state. Yes, I know that's staying a lot. Yes, I mean it. Please recheck your weight/balance after you eat there.
This one is a sleeper spot: if you come through on Friday or Saturday (only days they are open), head to Woodlake and eat at the cafe there. Everything is homemade and AMAZING. The sectional shows the field as turf, but it's beautifully paved. The ramp is crap though, as is the taxiway. Back taxi on the runway to the restaurant, and be careful on the ramp. It's a mess. This place just might be my favorite. I wish more people would fly here.
Enjoy!