I used to do it a bit ten years ago....most I went in a day was from Palo Alto to San Carlos in the hills along Alameda de Las Pulgas, about 9 miles.
At twilight yesterday we were coming home from a Billy Talbot (ex-member of Neil Young and Crazy Horse) show in Pescadero and drove along a mountain road and there was a guy biking up the ridge along Skyline -- I thought that was impressive.