The only touring route where you can do hostels is the Icefields Parkway between Jasper and Banff. You'll need reservations. Aside from that, I'm not really familiar with any touring routes around here, I just do the occasional weekend ride from Edmonton. My system basically involves looking for a B&B that I want to stay at and then figuring out the route to get there. There's no hostels outside of the cities and the mountain parks, so you're left either camping or B&Bs.
Driving up in March should be fine. There will likely still be snow around, at least part of the way, but the roads should be perfectly safe.