Sushi in S.F.
With due respect to those who feel differently, I've made it no secret that I'm not a fan of Ebisu. Though I have heard good things about Sushi Ran.
If you've got only one night, I'd recommend Kabuto (Geary and 15th). If you go there, wait however long it takes to sit at the counter.
I'm sure there are many others, but for fresh, unique sushi in the city, my vote goes to Ebisu. It's near Golden Gate Park (9th Ave. & Irving). They do some very interesting rolls (yes, I know, I'm a blasphemer), and it's a low-commitment trip.
However, if you have the time to make an evening of it, definitely take the ferry to Sausalito and visit Sushi-Ran. I don't think I've had better fish in the Bay Area. And, they have an exceptional selection of sake to choose from.