What scenery are you looking for?
Montana is plains, forests, mountains, depending on where you are.
Utah is mountains in the northeast, and along the eastern edge. Desert where it is not mountains, carved up into canyons on the Colorado Plateau. Southern half, the eroded rocks are red, as they are in northern Arizona. A lot of National Park Service properties on the Colorado Plateau.
Utah has the Great Salt Lake, Salt Lake City, reservoirs on Colorado and Green Rivers. Montana has Flathead Lake, reservoirs on the upper Missouri system.
Yellowstone NP would be at top of my list to revisit, touches both states, a little bit of Idaho, but most of it is in Wyoming.