I have ridden brevets organized by SFR, Santa Rosa and Davis Bike Club. They are quite similar, though Davis brevets tend to be supported by more volunteers, whereas Santa Rosa and particularly SFR rides tend to emphasize self sufficiency (i.e. spartan support). The routes are also pretty similar. San Francisco does run an "Adventure Series" with off-road sections and lots of climbing, but these are far from the norm. For example, SFR has a 200K to Winters this coming weekend, covering roads typically used in Davis brevets. I really like the November 200K to Del Puerto Canyon, definitely worth a look.