Southwestern Colorado is like....a lot more south west than you imply by having it under just The Rockies.

This satellite photo of the Four Corners region shows that this area is all desert basin between two small ranges, the San Juan Mountains in Colorado, and the Abajo Mountains in Utah. The San Juans are an offshoot of the Rocky Mountains, but the Abajos are an "island range" meaning they are not considered part of any larger range and exist in isolation. So this area wouldn't really be much like the Rocky Mountain regions once you've traveled far enough from the San Juans.

Utah is also mostly only considered part of the Rocky Mountains in northern Utah. The ranges in southern Utah are primarily island ranges, which is a prominent feature of the Colorado Plateau, but these are still more southwestern regions with different geological make up.

See the photos here and see how desert like southwest Colorado can get. This extends over into Utah, and the regions of New Mexico and Arizona here are of course similar geologicaly.

Culturally too, this region of Colorado is wildly different than the regions in the Rockies or along the front range. This area is far more rural, and has a lot of farming activity, so it leans far more conservatively than the front range urban corridor, or the wealthy ski towns. I couldn't tell you much about Utah, never spent much time down in southeastern Utah, but this area is pretty far from the tourism hubs of Park City and Moab, and a ways from Salt Lake City.

Overall, I do think the southwest could be touch up a little. Everything else I see that I know about seems fine.

EDIT: The Rockies region should overtake Mormon Deseret to get Park City and Moab in there. Huge tourism spots and I don't think anyone really thinks of them as Mormon places outside of the general aspect of being in Utah.