Rice wrote:
Also, watch the closing (or opening) date of the Going to the Sun Road in Glacier NP. We wanted to get there in 2011 but just didn't have enough time by going to the Tetons and Yellowstone after Labor Day. Depending on your travel style, it could be pretty tight getting to the Tetons, Yellowstone, and Glacier between Labor Day and the road closure.
However, if you were to approach from the north, you could do Idaho and Glacier before Labor Day. Surely they're nowhere near as crowded as Yellowstone. And you could schedule to get to Yellowstone after Labor Day, and then head to South Dakota.
This is what I would do.
Check the Glacier NP web site for typical dates on GTS road. With an average snowpack and no late snowfall, it's normally mid-June. One year it was July 10.
