We will be driving from Dallas to Grand Junction for a family reunion the middle of October. The drive from Dallas to Santa Fe/Albuquerque is long and boring but looking for suggestions for 2-4 days (flexible) after that. We went to Monument Valley, Grand Canyon and the Utah parks in the spring so are hoping to drive from Durango up 550, weather permitting. We are not going to be hiking, unless a short one, but interested in scenic views, Native American sights or museums, a great place to stay, etc. Also any exceptionally nice places to eat or picnic. Thanks for the help!
Prioritizing Rte. 550 north from Durango is indeed the way to go. You'll see some of the prettiest scenery in Colorado at about the time the Fall colors will be peaking.
Potential side trips that spring to mind are the National Parks at Mesa Verde, Great Sand Dunes and Black Canyon. A bit further off your route is Rocky Mountain. Going via the Grand Lake entrance would be my suggestion to keep from driving all the way around to Estes Park. Fall River road will likely be closed by then, but there's plenty to see on the Grand Lake side, plus it's just a pretty little town - it's where we base ourselves for annual trips to RMNP.
Just north of SF is Taos, and just off 550 is the very pretty mountain town of Telluride ... worth a day or an overnighter if your schedule permits
Taos is fabulous and has the Taos Pueblo - a fascinating site: https://taospueblo.com
If you enjoy hot springs, you might want to try Ojo Caliente, about an hour++ north of Santa Fe. Or, you could spend a night in Pagosa Springs (just a bit sulphur-y), just over the border in Colorado. Ghost Ranch/Abiquiu has spectacular scenery; you can ride horses or take walking tours at Ghost Ranch. Taos Pueblo is spectacular, but be sure to check to see if it is open to visitors. Sky City of Acoma, just north of Albuquerque (on the way to Santa Fe) is regularly open to visitors; haven't been there in years, but liked it very much when I was there.