Trip to Banff, Lake Louise, Jasper: advice?

I think we saw folks with rigs of maybe 24 feet at Wilcox -- but it was very darn tight. The roads in the campground are laid out in a series of hairpin turns as it ascends the side of the hill. We camped there in our 14 footer, but even that took some careful jockeying.

You might be better off at the Icefields itself -- we saw many big rigs in the lot there. It is not pretty -- just a parking lot -- but the views are amazing. The views at Wilcox are not panoramic and are mostly obscured by trees, as you can see: