Originally Posted by platypus
in what general area were you thinking? It's an old standby, but the Portola Valley Loop would pretty much meet those restrictions. It's not too tough, it's absolutely lovely, and there's lots of other bikers on the road.
I'll agree with Platypus. Palo Alto, through Portola Valley, to Woodside. If that's not enough, head north on Canada Road (especially if it's on a Sunday, since they close the road off to cyclists only that day).