If it were me going from D-M, I'd plan the day. Its' one of my favorite roads to ride. Just my opinion.
I couldn't agree more!
If you're taking 550 there is so much to see and do that you would be remiss in riding right by.
But that's o.k. too as some folks just like to ride.
I'm more of a "plant your boots in the dirt" kind of guy and like to soak up the local scene as much as I can.
Here's a couple of stops you should make along the way if time allows..
Box Canyon Falls in Ouray (You Ray) is a nice stop to see an incredible water fall inside a cleft in the rock. Costs a couple of dollars to get in but worth it.
If you are over on 145, the San Juan Skyway, be sure to stop at Mountain Village instead of going into Telluride. From Mtn Village you can jump onto the free Gondola and ride it down into town. It's free parking and the gondola ride into Telluride from the Village is something you'll remember for awhile!
Just a peek at what it looks like coming out of the top of the mountain and down into Telluride.
Of course if you are in Montrose you really shouldn't miss highway 92 up to Crawford (home of Joe Cocker) and back. It's the north rim of the Black Canyon of the Gunnison and a road that should not be missed.
From Montrose to Canyon City you should allow 4-5 hours drive time but be prepard to stop and smell the roses along the way.
Have a great time here and be safe.