Join Date: Aug 2014
Location: Dawson Creek, BC, Canada
campgrounds will be sparsely populated after Labour Day; I wouldn't worry about that.
I highly recommend the Icefields Parkway between Banff and Jasper. One of the most spectacular drives in North America (and enough curves to have fun in the Elise) - in good weather. Check the road/weather conditions when you get close. In bad weather you won't see much of the great scenery and at that time of year, snow is at least as likely as rain at high elevation... not much fun in the Elise. Either way, watch for critters on the road.
Not sure of your intended route but for fun driving overall, stay in or west of the Rockies. Long, straight and boring roads dominate the flat ground on the east side of the Rocks.