We went in September in a 26ft Motorhome. Hwy 93 was great...except there are a few pretty steep grades. We took hwy 93A from Athabasca Falls toward Jasper, very pretty.
We purchased an annual National Park pass for each of us. We did not make reservations....but had to be at each nights destination early to get a spot and to take what ever was available. Some small campgrounds are very tight for larger rigs. You can see the scars on the trees ;-).
It was a great trip...so much to see. We just touched the surface. Think it would take about three trips to do it justice.
Thought that there would be a lot fewer rigs after school started...but there were a lot of Europeans who had the same idea. Lots of Fraser /
Canada Dream / Cruise Canada rental motorhomes ;-).