Agree that supermarkets in the right neighborhoods are usually good choices. You might try the Brentwood Country Mart complex also. Another place that has good hits later at night is Ralph's Grocery in West Hollywood.

Gelson's in the Palisades, Century City, and Encino are also options.

I would also suggest the Katsuya in Encino on the restaurant side. Even if you do not spot anyone, the food at that location is the best of the chain, and the location is not pretentious.