I am planning my summer trip to see family (I am from Idaho) around the eclipse. I currently have hotel reservations in McCall and Boise. From Boise, I would recommend driving 2-3 hrs to Stanley basin. This is a beautiful area in and of itself with the Sawtooth mountain range, Stanley Lake, Redfish lake, etc. From Boise you could also drive west on I-84 for about 1.5 hrs. This is sagebrush/hill country. Pretty, but in a different way. Or you could drive north on SR-95 for ~ 1 hr to near Smith's Ferry. My issue with this location is that the canyon is fairly narrow along SR-55 (pretty) with few spots along the road to pull over. If I end up along SR-55 I am going to be checking a lot of things prior and will likely shoot for a dirt road on a mountain top with a more expansive view.

A big plus for Boise, all the above are in a rain shadow of the Cascade Mtn range. Great chance of no clouds. A big negative...peak fire season. Roads in the forests could easily be closed and there could be a lot of smoke (granted, they got a lot of water this year). In short, Boise is a good spot, but there are still risks.

That said, I would also be looking in the St. Louis/Knoxville/Nashville area. That is the spot with longest duration....and could add on Great Smokey's NP and some waterfalls