We were in GNP last week and had an awesome time. Got to see a grizzly bear near Many Glacier and saw many mountain goats. The park is majestic in it views from every where you look. See a few attached photos. We looked at the CG at Many Glaciers and asked the camp host about sites and her recommendation was to get there by 8:30 AM on the busy weekends to get a site middle of the week wasn't as bad and like others indicated 10AM is probably fine. We actually stayed in West Glacier at the RV Park less than a mile from the entrance. Full service sites in the woods and not too packed together. Clean and friendly folks. They even had a backwoods restaurant that was run by a kid from the local culinary school. We enjoyed great BBQ ribs and he also does a great breakfast. It was a nice break in the travels.
Enjoy your trip. I can't wait to return again.
Cheers,
Bigcgar and Vicki