Hunter4623: Be sure to do the Badlands National Park in South Dakota, then Custer and next do Mt. Rushmore and Chief Crazy Horse Monuments then do Devils Tower in eastern Wyoming, then spend a FULL day (before sunrise to after sunset!) on both "roads" in the Bighorn Mountains of Wyoming then a full day in Cody, Wyoming and the wonderful museums there. Then for sure try to do the Beartooth Highway in Montana (if it is open on your way out or your way back).
For sure do Yellowstone Park if open and right next door is Jackson Hole, Wyoming which is blisteringly beautiful in spring times and is open year round.
Eat at Bubbas in Jackson Hole, Wyoming (breakfast, lunch and dinners!).
Once done in Jackson Hole be sure to mosey over to "the Wind" - stunning, this area of Wyoming, and do some road exploring or short hikes.
Watch for shed horns in your travels and good luck on the spring Bear Hunting.
If you are a gun-nut type be sure and stop in at Shedhorn Sports in Ennis, Montana (just north 75 miles or so of West Yellowstone).
Enjoy the scenery in the Madison River country between West Yellowstone and Ennis.
Have fun - drive careful and steal TP along the way!
Hold into the wind
VarmintGuy