We stayed at St. Mary KOA a couple of years ago for a week. We liked the fact that the east side is very quiet compared with the west. The entrance and visitor center are right there. We took the tram from the visitor center, which is a really nice option going across Going to the Sun Road. There are many stops along the way. You can hop on and off many times if you want. There's also a KOA on the west side that also looked nice. There were many other good-looking campgrounds in the area. The bustle of the town on the west side didn't appeal to us. The east side vs west side is probably a bigger decision than the campground you choose.
2017 Melbourne 24k towing 2003 Jeep Wrangler
2013 Premier 19FBPR; 2013 Rpod 177 HRE
2011 Aliner Sport; 2008 Little Guy 5-Wide
1980 Shasta 21; 1981 Coleman Tent Trailer
1978 VW Westfalia; lots of tents