Help!  Advice needed for my upcoming trip to CA.  I’ll have two nights in San Francisco, and I want to make the most of it since it’s one of my favorite cities and on my “Places where I could imagine living” list. The plan is to walk the city ’til my legs fall off and eat ’til I have the Joey Chestnut face going.  I’m most interested in gourmet markets, hidden ethnic gems and eat-and-go kinds of places. Any and all suggestions are welcome and much appreciated!