it all boils down to... do you have a car? and are you willing to drive?

accessible by Muni (Bus - Public Transportation):
* Hobby Company (on Geary st. lousy selection, lousier prices);
* Franciscan Hobbies (on Ocean Ave. Bigger selection, but still lousy prices);

take Bart (Subway - public transportation), and catch a cab...
* RC Tech (Daly City, i haven't been there yet. and if you search and find the one on Geary St, that's long gone)
* All Speed hobbies (located in South SF. good parts selection, when i visited 2 months ago they had just finished moving, as such they were restocking on their kits);
* Boss Robot (located by UC Berkeley... across the bay, and a short hop from my house. they can get almost anything i need. as such, they are my store of choice)

Just gonna rent a car and Drive... (sorted by distance from SF)
* Talbot's Toys (San Mateo, great toy shop, lacking in the RC department)
* Victors Hobby (Newark, tons of plane and heli stuff)
* Norcal Hobbies (Hayward/Newark. mainly cars, and parts. they have some planes and helis, their main draw is their car track)
* Aero Micro (Santa Clara, excellent selection of airplanes/helis)
* Sheldon's Hobbies (they've changed owners! we'll see how that works out... but they're in Milpitas & San Jose)
* DJ Hobbies (South San Jose, i haven't been here in years, but they had lots of stuff back in the day)
* Hobby Town (chain store, locations everywhere, just search their website)

These are just off the top of my head, perhaps another member can shed some light on additional places i missed.
but basically, in the city, there ain't a whole lot of selection. you need to go outside from there.
have fun at the wedding. oh, and bring some warm clothes to layer with. May can be deceptively cold... and it can also be really warm once you pass the fog belt. go fig.