Here's a list of California rides by date: http://www.bbcnet.com/RideCalendar/RideListDate.asp

It's been a while since I did a century but I've done the Sierra Century. It was a beautiful, well supported ride.

A friend of mine organizes the Tahoe Sierra Century. It's for a great cause: music instruction in the middle and high schools.

The America's Most Beautiful Ride around Lake Tahoe is just that. Unfortunately it's already full. The Team in Training has basically taken over that ride.

You can check out the whole list. There's a ton of them.