Another option would be to start as planned in Denver and do a roundtrip through Colorado. I would like to do the trip from Durango to Silverton by train - this would be a nice event on the trip, so the trip should be clockwise. SandDunes on the way and back over Loveland or RM NP. Maybe we will make a break in Durango for some 2-3 days, rent a car and do a roadtrip ...