As part of a whole other project, I wound up compiling a selected list of yarn/fiber shops in the San Francisco Bay Area (to include San Francisco, the counties of Alameda, Contra Costa, San Mateo, Santa Clara and Monterey).
I do not have any entries for the north bay counties (e.g., Marin, Solano, Sonoma, Napa, etc.). If you have any recommendations, I'd be delighted to include them.
In the meantime, HERE is the first draft of something I hope to continue updating. Enjoy, and happy shopping!