I've been looking at doing one myself. I live near Morrison and was thinking: Morrison to Evergreen, Hwy 103 to Idaho Spgs, Hwy 40 to Winter Park-Granby-Grand Lake, then Trail Ridge Rd to Estes, back through Allenspark, Nederland and Golden Gate Canyon to Golden, then back to Morrison. I'm planning on going in July as there's 3 mountain passes and I'd like them to be free on snow and ice :-)
Edited: try this link to see the route:
http://maps.google.com/maps?f=d&sour...6,4.221497&z=9