That is a tough one. Sunnyvale isn't a hotbed of excitement. And the SF commute isn't too great (but maybe if you are Caltrain close, it isn't so bad). Although I'm no expert on that area (my brother used to live in Sunnyvale), I'd think that Mountain View may be the best closer place if you want to live down that way. If you are wanting to live in SF (and I can't blame you), you will definitely want to be close to Caltrain, which means a more downtown/south of Market residence. From there, you'll be close to all the excitement you could want, for the west coast. Union Sq. area is all about the shopping. If you had taken a 15 min. walk through the Stockton St. tunnel to North Beach, you'd have found a lot of good eats and people out. For you, my instinct is SOMA or Inner Mission. But maybe I'm wrong.