I haven't spent a lot of time in the Rockies, but for the most 'bang for your buck' you might want to scoot over to Jasper then drive to Banff on the Icefields Highway. It'll get you into alpine and take you through some jaw dropping mountain valleys. This is a MUST DO when visiting the Rockies.
There's also a book in the stores there called something like, "Easy Walks and Hikes in the Canadian Rockies". It has information about short trails leading to lakes, waterfalls, etc. that start right beside the road that you wouldn't even know existed without the book. If you're short on time this book would be handy.