Can't go wrong there on the Icefields Parkway thats for sure, as I finally travelled Hwy. 40 northbound for the first time last September in my camper rig.
The majority of stretch between the Hwy. 16 Junction and Grande Cache is very narrow shoulder, however most of the road surface is pretty nice between there, as north of Grande Cache generally has wider shoulder with great road surface.
There are many designated passing lanes along the foothills and grades so no problem there either, as the Hwy. 40 route is certainly not a boring drive at all and a relatively easy drive.