First, excellent idea for a thread.
Silverado Canyon
This canyon climb is a great low traffic, out and back climb. The warm up is along Santiago Canyon Road - while it has a fair amount of high speed traffic it is also rather scenic:
After the warm up, you turn right onto Silverado Canyon Road. The first half is a gentle grade that goes through the town of Silverado:
The last half is a gorgeous, increasingly steeper section that is often closed to cars (this is the Maple Springs Trailhead section):
Overall, the climb gives you a bit over 2000 feet of elevation gain (in addition to what you climbed on Santiago Canyon Rd). The Maple Springs section gives you 3 miles of 7%+ climbing.
The route map can be found here:
http://www.mapmyride.com/view_route?...1&rs=undefined.
My ride report, with more pictures, commentary and maps can be found here:
http://www.toughascent.com/blog/?p=45.