Scenic Routes/Places to See in WY, ID, MT, SD & E. CO

Island Park, ID can be a good base camp for at least some of Yellowstone (about 15-25 miles from the west gate of the park, depending where in Island Park you land). From there you can also spend 1/2 day or so at Mesa Falls (beautiful)! and even head up to Virginia City MT - old mining town - or Hebgen Lake area (Quake Lake, etc.) Or south from there to the Tetons, via either ID 33 or (better route for RVs) US 26 - longer drive but pretty. Definitely you'd need reservations in the Tetons unless you can dry camp.

Craters of the Moon NP is a neat little park, and very different. You can camp there (hot & you have to dry camp) or base camp in Arco ID, about 20 miles east of the park; on US 20.

Tyler0215, Islandman, thanks for your input! Much appreciated.

JAC1982, we look at I25 as the east/west division point for CO. We've given some thought to visiting Pikes Peak. That's about as far west (into CO) as we want to go on this trip.

When you say "Eastern" Colorado, how east are we talking? Actual Eastern CO doesn't have a whole lot of scenic anything as it's all flat and farming/ranching.

In WY there's too much to list... depends on your route.

Several favorites we have enjoyed over the years: (1) MT 509 from Henry's Lake, ID west to Monida, MT in the Red Rocks Country, (2) MT 278 and MT 43 from Bannack northwest to Chief Joseph Pass thru the Big Hole Country, (3) US 12 from Lolo, MT westward to Lewiston, ID along the Lewis & Clark Highway and the Lochsa and Clearwater Rivers. Good camping spots along US 12, stop at the visitor center on Lolo Pass for more info.

There's much more to see at Rapid City beside Mt Rushmore,the badlands, hill City Dinosaur dig,Lead, Sturgis. A side trip to Devils Tower In WY.
Cody as a great museum.