If you want to search APUG, up in the upper right hand corner there's a Google Custom Search window - type in your search terms and click the magnifying glass. Or just go to Google directly and type in your search terms and you'll get results from here, LF Info, Photo.net and a host of other photography websites too. I apologize if I am (or anyone else here) being a little brusque on this question but this is a relatively common kind of request that is easily found by doing your own research first.
If you want a lab in San Francisco,
LightWaves looks like your best bet, as they can handle C-41 processing up to 12x20 (yes, 12x20!!!!). If you want to do your own processing, but just need the facility,
Dead Link Removed is the place in San Francisco to go.
With that said, welcome to APUG, do enjoy your trip to Yosemite, and please post your results to the gallery! If you do find a lab close to Yosemite, please share your impressions of their work, as I'm sure there would be a lot of people here who would love to know about it. If you use one of the San Francisco labs, also please pass along your opinions. Because labs change all the time, up to date info on available services, prices, and results is very welcome.