We arrived in Kalispell around the 20th of May and spent 10 days on the west and east side of Glacier then on to Waterton National Park in Alberta. It was great. We then drove through Calgary and up in to Banff. Agree with the earlier post about the drive from Calgary to Banff as just beautiful. Canadian schools don’t close till near the end of June so not crazy busy but there were crowds. We found the campground at Lake Louise to be a bit quieter than Banff, more to my taste as well. Highway to the top in Glacier did not open until arond 4th of July, so we did miss that.
Consider making a loop, time of year will matter.