We were in Glacier, Yellowstone and The Grand Tetons in 2019 at about the same time. Everything is busy, parking is limited, everyplace is crowded. You either have to deal with it or not go. We had a great time even with the crowds.
Be careful about the weather. On about Sept 12 we went over the Bear Tooth Highway. We started early to see the Lamar Valley. By the time we left the Top Of the World store near the summit of the Bear Tooth, it was snowing hard, the road was covered by snow and they closed the road about 15 minutes behind us. We made it through without a problem but had to take a 150 mile detour to get back. Weather can be a beast that time of year. Still one our best trips ever.
