There is a small place called Darwin Cafe on Ritch which I like. I haven't been there in about a year but I hope it's still as good as before. Very fresh ingredients. The chef came from Boulevard.
The burger at Marlowe is good.
You should probably try the grilled cheese at The American Grilled Cheese Kitchen at least once.
If you are there at lunch, there is a food cart on Ritch between Townsend and Lusk that serves chicken and waffles, which I'd recommend.