Mesa Verde is an amazing place. Be sure to stop FIRST at Far View Visitor Center and buy tickets for the tours. I recommend Cliff Palace. And if Rebecca sells you your tickets, be nice, she's my goddaughter
. The loop drive is also fantastic - you stop and look across the canyons at the ruins, a different aspect than being in the ruins.
The train from Durango to Silverton is incredible and is absolutely worth the money. Take the train up and the bus back down so you see different things. If you can't do the train, then for sure do the Million Dollar Highway drive.
Hovenweep National Monument, 45 miles west of Cortez, is a very special place. Much less developed than Mesa Verde and more like you might accidently come across the ruins on a hike or ride.
If you've got a 4WD, do the Alpine drive, into the San Juan mountains from Silverton. You can not belive the scenery on this drive. And you can easily climb a 14er (14,000-foot mountain) since you're over 12,000 feet in many places.
Any other advice you're looking for just shout out. We've lived in the area for over 20 years (Hovenweep National Monument and Cortez).
Enjoy
Wendy