Alex is the best. You're not going to get such expertise and wine commentary in other stores. Period.
Moreover, the selection is fantastic, and prices are very fair. Even if places like K&L have more bottles, in total, they don't have quite as many interesting and tasty ones. Everything from Sherry to Jura, with lots of great Burgundies, orange wines, and much more. I completely disagree with Aaron F's comment of "there are no deals to be had here." Alex can pick out the best deals for your price range and desired wine qualities.
This is easily one of the best wine stores in the Bay Area, and definitely the best one in a wide radius.