Random thoughts:
Day 1, I concur with others to be aware of altitude sickness, etc.

Day 3, consider continuing onto Durango instead of stopping in Pagosa Springs. Chimney Rock is west of Pagosa and would be a good late afternoon short hike, though it likely will still be hot. Walking around Durango in the evening would probably more interesting than Pagosa.

Day 5-6, going east from Utah, your best bet for a group of wineries on this trip (IMHO) will be in the Grand Junction, Palisade, Delta area. For reds, some of my family are a particularly fond of Reeder Mesa winery, south of Grand Junction.

Last few days, particularly if you are thinking of using Marriott or Starwood points, look into the Flatirons Renaissance or the Westin Westminster, respectively. From either of those it would be easy to cover Boulder, Denver, and Rocky Mountain National Park. The Westin is adjacent to a great restaurant/entertainment complex; the Renaissance in close to a large shopping mall and area. Denver Museum of Science and Nature is excellent. In the same area are the Denver Botanical Gardens, which will likely be hot to walk around in during the day but open into the evening usually.

I would respectively disagree with my fellow Front Ranger on one point: if you want to do Steamboat, then route through Steamboat on US 40 rather than trying to hit it while staying somewhere on I-70. Grand Junction-->Dinosaur NP-->Steamboat-->Granby-->Rocky Mt NP --> Boulder area is certainly a viable route (more than one day). The road across RMNP has some great scenery but also gets into significant elevation.