That will be a great trip. Chief Joseph Highway from Cody WY up to the Beartooth Hwy just NE of Cooke City is a must ride also since you are in that area. two points for consideration.

--Don't try to see too much. Banff and Icefields Parkway to Jasper are awesome, as is Lake Louise, but ensure you have enough time for Yellowstone, Tetons, Beartooth, Chief Joseph Hwy, and Glacier (must ride west>east or east>west all the way up over the pass). Beautiful!!!! Important to watch the weather in September. Beautiful time of the year and should be good weather, but watch for a passing cold front that could dump snow in that whole area. Make adjustments accordingly.