For real Mexican down home food, try Orale! Orale! on the foot of Sacramento Street across from the Embarcadero Center. Wander down Columbus Avenue in North Beach for California style Italian food - some are **** (Four star) and some just have really great ambiance.
Try any of the restaurants in the Ferry Building.
In Chinatown, it's Tommy Toy's. Out in the "Avenues" on Clement, eat at Yet Wah. Very good Szchewan style!
For Vietnamese/French, go to the Slanted Door, but make a res.
Enjoy the City. It's the best place on the edge of the Earth.
I have lived withing 50 miles of the city for my entire life!