Four of us met up for this ride. 29.2 miles, 2:45 active riding time, about 4:30 total including a break for lunch and a beer in Port Costa, a stop to photograph miniature horses(!), and so on. Lots of scenic, rolling hills, and not much traffic.
Approximate route: http://www.gmap-pedometer.com/?r=2924086
I’ll post a few photos shortly.