I love the fall, to me it brings both amazing sights and the promise of winter. Fall in and around Yellowstone is even better; with clear sky, warm days, cool nights, spectacular colors and a kick into gear of all of the parks wildlife.
Fall brings about a boost to wildlife activity in the park. Most visitors come to see and photograph the elk and moose ruts, and I have done that many times too, but this fall I spent countless hours with a very friendly fox.
For me the most spectacular part about fall in the mountains is the changing color of aspen leaves. Clear blue sky mixes with the yellow, orange and green of aspen leaves in a way that is beautiful beyond words.