That will be a great time to travel through there. It is after the "tourist season" and before it gets too cold. It has been a few years since I have gone through the Rocky Mountains but the mountains do not change that much. For me I was just shooting 35mm at the times I've gone there and your best chances are the early mornings. In the mornings the air is clear and cold. Take a few extra warm things with you eg . wool socks, light movers gloves (good for fine adjusting and focusing) a warm jacket, sturdy boots. If you have time check out some of the small lakes through there. Lake Loise and Miette Hot Springs are a few beautiful locations. But beware if you do go off the "beaten path" the bears that may be there are not particularly fond of people. And listen to the locals they are the ones who know the area and the hazards. Have fun and shoot lots.