Canada
We usually avoid national parks, in favor of national forest wilderness areas, but the Canadian Rockies are so good it is worth the beaurocacy. Particularly in late season, you can find much solitude and some game. We declared Wonder Pass the prettiest place we had ever seen. We have carried easily a dozen trips in our head for years.
There is some spectacular backpacking to be found in British Columbia, in the ranges to the west of the Rocky Mountain trench. There are four ranges found in the unofficial “Kootenay Mountains”. The best, and one of our personal top four, is the Purcells.  Go anywhere in the Bugaboos, or Jumbo Pass, or up Hamil Creek to Earl Grey Pass. These areas are generally within less regulated provincial parks.
Some consideration is due the Selkirk range, perhaps in the Revelstroke or Grinnel Lakes area of Valhalla. You will no longer notice the American end of the mountains.
                   Wonder Pass views, Banff