Took the kids there a few years back, stayed in town at Townsite Campground. Its run by the park service. Really enjoyed the campground and the kids liked the access to the town.
I found Cameron Lake worth the drive. The opposite end of the lake is in the US.
Kids very much enjoyed Red Rock Canyon. Bring towels, swim suits, and shoes you can walk in the water with. Reminded me of the Narrows in Zion, though the walls are not nearly as high.
We were there in late June, right when the mama deer come into town to birth their fawns. Deer everywhere.
As for Glacier, my fav campground is Many Glacier. Its fairly isolated, like two medicine, but the hiking access and views are second to none.