If your going to Montana I would recommend "Going to the Sun Road", "Beartooth Highway" and "Cheif Joesph Scenic Hwy". Some of the best rides in Montana/Wyoming. Check out Red Lodge, Mt. Neat little town. If you are down there I would tend to stay out of Yellowstone as the traffic will be really slow moving at this time of year. As for southern BC, as mentioned by others the area north from Creston through Nelson, Kaslo, Nakusp is some of the best riding in western Canada, just plan on taking some time for riding ferries and stopping in small towns. Beautiful but don't plan on big mile days.