I've been to Buffalo many times. Visit the Little Bighorn Battlefield or Fort Phil Kearny (Fetterman Massacre site). They're both very interesting and one-of-a-kind
If the weather is decent fishing The Miracle Mile or Grey Reef are worth giving a shot. Frontier Canyon is a sight worth seeing also. I spent 3 days fishing these areas on the North Platte in 2021 before an archery antelope hunt. Beautiful river and there weren't a lot of fishermen. Only 1 other guy in Fremont Canyon. There are quite a few public access places or you can hire a guide at one of the many fly shops.
Used to stream & small river trout fish a lot before moving to FL and kinda miss it. FL has other kinds of fish...but is much different than fishing a stream or river. Will spend at least some time fishing for trout.
Just want to make sure we see the "other" stuff that needs seeing.
Hunted near Devil's Tower couple years back and enjoyed that plus Mt Rushmore on the way home. They were well worth the time to see.
Seconding Frontier Canyon and Grey Reef. No idea what the conditions are like currently, but when I fished the Platte a couple years ago it was our most productive hole.