Having photographed those areas quite a bit, the 80mm might not be a bad choice. The wider angles are tough in Yosemite as well as Death Valley, mostly because you get so much sky and foreground that it detracts (kinda unusual) from the larger scene. Death Valley is a strange place because it's the only place I can recall where I wanted the longest lens possible.

Utah, on the other hand, needs a wider lens for most of the grander areas, although the 80mm would be more than enough for things like Delicate Arch, Island in the Sky, and Powell.

Buy a copy of Desert Solitaire and take Abbey's advice, get out of the goddamn automobile and use your feet. Then the angle of the lens is less of an issue