Glass Key Photo at 448 Haight Street in San Francisco is a great place to visit. They are inside of Rooky Ricardo's Records, itself a great shop; Glass Key has hard to find film, paper, ink and chemistry ... and if you have a turntable (and like old fashioned bottled root beer) you will be in heaven. They even carry 127 format.
UPDATE: They're moving right next door to their current location. They should be there by Tuesday, October 16th. I was just there Sunday and the owner told me the news. Also, next door to Glass Key, there is a little art gallery with some paintings and a few pictures. Go visit them.
Agree about Glass Key. Competitive prices and a small but very good variety. They carry Adox paper!!