Hwy 35/Skyline Blvd. Portion of it that goes through the heavy forested mountains, just south of SF, in the Bay area, had been always my go to road for riding my motorcycle to hit the mountain twisties. Never rode my bicycle through there because of the fast car and motorcycle traffic that regularly ply those twisties (And the CHP that regularly chase them down when they speed). Although there are enough bicycle riders that goes through Skyline/HWy 35, that enjoy the mountain rides.