I have. I rode from Ouray to Telluride over Dallas Divide. The problem with that ride is coming up the canyon, the road was narrow and winding (hey, its the mountains!) and it had a fair bit of relatively fast truck traffic. Not fun. I also rode from Telluride to Dolores over Lizard Head Pass. You go outa town and turn left (about the only paved left you can make). That was a far nicer ride. It had a lot less traffic. You could do that on an out and back basis. I would advise not to go beyond Lizard Head Pass though because from the pass to Dolores (which is a nice ride to) it is all downhill. So it would be some work to get back to Telluride.