It has been a long time since I lived in SF, so hopefully my comments are still accurate.

Bread bowl at Boudin's is a must.

You didn't say if your gf likes fancy or good food.

Good:

Burma House is gone, so look into Burma Superstar. It is like Americanized Chinese, but isn't.

Cha Am - This is an upscale Thai place across the street from MoMa. Depending on your gf's tastes, and what is currently at MoMa, they are a good combo.

Yank Sing - Dim Sum in the Financial District. Upstairs is the typical loud huge sea of tables with carts wheeling around. Downstairs is a much smaller area with quiet private booths. Best seat (in my opinion) is the booth for two right in front of the kitchen. First pick of everything.

Fancy:

The Grand Cafe - This place impresses without bankrupting. The bar is great, the bartenders are good. The restaurant is visually impressive and the food is solid. The gf can dress to the nines and you can get away for about $100. $200 if you spend too much time at the bar or get into some wine.

Neptune's Palace - best view of the bay. Grab and early lunch there to score the best view. I think the food is, uh, boring. The seafood is fresh, but the prep is bland.