Jeff Wilder said:
As a resident of the Bay Area, I've never found Gamescape to be anything special.
yeah, I didn't see the big deal when I was over there. It's just a store.
Jeff Wilder said:
Endgame -- In Oakland, about a block from the City Center BART stop. They have an incredible, roomy display area, and a phenomenal play area, containing about 10 tables, built into a loft.
my god, I have probably walked past this a dozen times and never knew it was there! will learn to keep eyes open.
Jeff Wilder said:
Games of Berkeley -- In Berkeley, about 50 paces from the Downtown Berkeley BART stop. Again, a really nice, open shop. The game area is kinda small, but workable. The main attraction of GoB is the friendliness of the employees and regulars.
As a regular of GoB, I resent being called "friendly."

I also know that one of the employees would similarly object.

Everyone else is fine, though, and the staff is especially good at helping you learn a new game or find something obscure or order something weird... They have a stranglehold on all things game, and do not want to lose it.
I live six blocks from GoB; know it inside and out. If you have any desire to hop on the train and ride the twenty-five minutes out to Berkeley, then do it. Get off downtown, go upstairs and cross the street, that's it! Lots of food and flicks around there, too, so you won't be starved for entertainment. If you're a FPS gamer, then there's a new store a couple of blocks north called Eudemonia that rents time on machines so you can blow your friends away, too. Eudemonia also sells WotC products, but...stick to Games of Berkeley. They have a flat 10% discount on most WotC stuff, and for the stuff that isn't on sale, you can solve the daily chess puzzler and get 10% off anything in the store.
GoB has game areas in the basement, in the back room, and a small table in the shop, usually used for Magic or something. I know that there's a regular Tuesday night Eberron/minis shindig, but I think they may not be playing next week. If you're interested, I can shoot the DM an email and find out for you. The store has all sorts of regular gaming nights:
http://www.gamesofberkeley.com/ I only know the Tuesday night crowd; I don't know what that Thursday night campaign is, but I may know its players, you know?
Secret: the manager plays in the Tuesday night bit, so they're there after-hours; you won't be chased away at 9pm, though your jetlag may send you home anyway. And after your PC is crushed by whatever it is that kills him, you can go a couple doors down and drown your sorrows in pizza, beer, and cookies.
As far as "essential" SF attractions, you will likely be quizzed on Fisherman's Wharf, so try to see that. It's just a big tourist trap, though, so eat your clam chowder, gawk at the sea lions, and run away.