Another fun thing is the boat trips on the lakes. They tell you lots of interesting facts and stories. Gives you a different perspective with some amazing views. You can get off and hike, then catch a later boat for the trip back. They run every couple of hours. We have done them all (there are four) and think that Two Medicine and Many Glacier are the best. Lake McDonald is kinda boring.
X2 on doing Arches first. Prime time at Glacier is mid-July to end of Aug. Also X2 on Jhonson's RV park if you want hookups, really nice views We love Glacier! Have a great trip.