Calgary, Stampede Week , if you don't already have reservations, you're probably not going to get them this year.
The place is a ZOO , during the Stampede.
Waterton Lakes N.P. Canadian side of the border from Glacier ; I've only stayed there in, mid Sept. and it was 3/4 full then. Mid summer they will be full; particularly on week ends. I'll see if I can post a link to a web site for them.
St. Mary, Montana , KOA, was our site for staying while we toured through Glacier N.P.. The main road through Glacier , wasn't open to over height vehicles, low tunnels & rock cuts. About 13 years since I was there , so any comments I'd have would be dated.