My wife and I are flying in to SF tomorrow. Our plan is to head to our hotel (the Market St. Westin, which is near the intersection of Third and Market) around noon, drop our bags, and get lunch before we head out to do some sightseeing. I'm looking for a quick lunch option (counter service would be great) but would prefer not to have to resort to a national chain. Any tips on good places to go in that area? A few blocks' walk is fine. Thanks!