I highly recommend going up to Jasper NP in Western Alberta and heading West from there, and a guided hike on the Athabasca Glacier is a must! Skip Banff and camp in Jasper NP for a few days then head West through the Kootenay's and ultimately end up at Green Point Campground, Pacific Rim NP on Vancouver Island. I am an advocate for "just winging it"... but info for reservations can be helpful:
BC Parks - Provincial Park Campgrounds: Vancouver Island & British Columbia