Here as in Washington, if it isn't National Forest, it's going to be open range land, with relatively straight and flat roads. Google Maps terrain mode gives more details.
Most questions about the area have to do with crossing from east to Yellowstone. For that the Big Horn Mtns are the main concern, with US16 easiest, US14A hardest. And going into Yellowstone, there's climb west from Cody, and another seasonal drive NW to US212 and the NE entrance.
And south of Termopolis the highway goes through a canyon, with at least on tunnel.
Otherwise, I think wind will be more of an issue than grades or curves.