this exact trip, But I’m guessing it’s about a 7 or 8 Hour Dr. to the Rushmore area in Custer State Park. He’s gonna want to go to the badlands national park while he’s in that area and maybe stay in wall drug. It’s a tourist trap but it’s got an appeal. Custer State Park is beautiful and is worth a couple of days if he’s a hiker.
I have driven From there to Yellowstone.
Yellowstone. It becomes an absolutely gorgeous drive. There’s a couple of different ways to go but my recommendation is to go from the Custer State Park area in South Dakota along interstate 90 to Sheridan Wy and then from Sheridan take the road through the mountains to Cody . I don’t know how much time he has but from Cody it’s less than an hour drive. Into the park at Lake Yellowstone. My normal recommendation however is to go in through the north east portal which requires going north from Cody via the chief Joseph Highway, a spectacular drive. If he does that he needs to take the detour up Beartooth Pass and back down. The north east portal brings you into the Lamarr Valley which I just love. All depends on how much time he has.
The way to go from Yellowstone to Vegas in my opinion involves going through the Southern exit of the park to the grand Teton‘s Jackson hole and then follow Highway 89 until it runs into interstate 15 in northern Utah, that’ll take you directly to Vegas. A great side trip is to get off of 15 And back on to 89 south Just south of Provo. From there Bryce Canyon and Zion Canyon are basically along the road. It’s three hours from Zion Canyon to Las Vegas.