if you have time, take a day drive out of Cody and drive the Chief Joseph scenic highway up to Bear Tooth Pass and down to Red Lodge MT and back to Cody. Great drive!!!! not for pulling a trailer or motorhome!
Cody to Ten Sleep to Buffalo and 90 on to Devil's tower. Crossing on 16 is the easiest of the three routes, but not a piece of cake, either. Going up out of Ten Sleep is not a hard climb. Going down to Buffalo is a lonnnnng descent, so watch your brakes. Other than that, it's a gorgeous drive, and there is water and a dump station up near the top of the pass.