Wind River Canyon, Wyoming

Even if you don't really care about rocks, the different units are worth seeing.
Chugwater Formation

Dinwoody Formation

Phosphoria Formation

Tensleep Sandstone

(top to bottom)Amsden Formation, Madison Formation (Mission Canyon Limestone), Bighorn Dolomite, Gallatin Formation, Gros Ventre Formation, and Flathead Sandstone.

Another exposure of the Great Precambrian/Cambrian unconformity: Precambrian granite and Flathead Sandstone