You could start by looking up campgrounds on the Canadian National Parks website. National Parks you could explore during your trip if starting in the PNW would be Waterton (hiking seriously effected by wildfires last year), Kootenay (the Rockwall is an excellent backpack which goes over several high passes above the tree line), Banff (busy but some nice hiking), Yoho (in my opinion the best day hiking National Park), Glacier (smaller, hikes are more demanding due to steep trails), and Jasper. Many nice hikes along the Icefields Parkway between Lake Louise and Jasper.
AN additional couple of hiking destinations would be Assiniboine Provincial Park and both Height of the Rockies and Top of the World provincial parks. The Top of the world is easier to access though it is possible to helicopter in to Assiniboine if you don't have time for the full day hike in.
You can PM me if you want more hiking information.