If you're staying in Berkeley, you gotta try Blondie's Pizza on Telegraph Ave. Best pizza by the slice on Earth.
In SF, check out Johnny Foley's Irish House on O'Farrell. Great drinks and atmosphere. They have a vegetarian Irish Stew which is really good, and if you like lamb, the braised lamb shanks are incredible.
If you like seafood, my favorite spot is Alioto's, on Fisherman's Wharf. They have good pasta there too. I'm sure your SO can find something to enjoy there.
Oh, and...skip Walmart...try Rasputin's Records on Haight for a touch of "local color". It's close to Golden Gate Park.
Speaking of Golden Gate Park, I've always enjoyed the California Academy of Sciences. It's got all kind of great stuff. Very cool.
Enjoy your trip!