SF is regarded as one of the great food cities. It's not the streetfood/cheap eats mecca like LA, nor the super high end like NY. It sits right in the middle and most things are in a good price range. Its hard to go wrong with food up there. Experiment, check yelp, or check out this forum;
http://chowhound.chow.com/boards/1 Wine country will be really good, whether you choose Napa or Sonoma. I didn't think wine tasting would be fun, but it actually is a great time out.
Would be more exciting if you can come out here in the spring/summer and catch a Giants game at ATT Park...love that park. If you wanted dinner and maybe some live music Yoshi's is a good spot. Here is the February calendar
Yoshi's San Francisco Jazz Club | Japanese Restaurant San Francisco ...seems like an R&B group is there performing as well as a pianist in the lounge