We were in Glacier last summer. We were coming from Minnesota so not as far as you. We stopped in Minot at a very nice state park. We always plan distance on 50 miles per hour even if you are driving faster. It allows for a few stops, slower traffic, etc.
We stayed at the KOA on the East side. While the campground itself was very nice and the location was great for the east side, if I did the trip over I'd only stay here a few nights versus our entire week. The only reason being that the wind on the east side was terrific and we couldn't even just sit outside and enjoy the scenery.
It's alot of driving just to get to Glacier and then once you're there you need to continue driving to get to other areas of the park, but the drives are all scenic and definitely worth it. I definitely reommend going to Waterton Lakes and if you have additional time heading up to Banff and Lake Louise.
Also, make sure to take one of the boat rides in the park. The scenery and relaxing atmosphere are very special. The guides also give additional information on the park.