I've never visited San Francisco before, but this summer I will be attending two conferences in SF (a month apart). The venues are in the Union Square and Embarcadero areas (near the financial district, I'm told). All lunches are on our own, and depending on the schedule, I have 60-90 min. for lunch. I would love some recommendations for good, inexpensive eats in the general area (I've already made note of recommendations for the Ferry Building on other Serious Eats posts, and will definitely make that one of my stops). I'm open to just about any cuisine (but have a weakness for good pannini sandwiches). Thank you!