It's been too many years since I was last in The City (local for S.F.).
I was there from 1971-1974. The thing I remember the best is the hundreds of small hole-in-the-wall restaurants with fabulous foods.
When I was there, Chinatown was a great day trip. However, not the place to be after dark. Street gangs were rampant there then and it wasn't the place to be after dark.
In Chinatown, lots of small shops for locals. Stay away from the touristy looking joints, they're full of junk.
Maybe a S.F. local will pipe in with some current favorite places.
Good luck! I wish I was going with you!