I've never biked from Calgary to Vancouver but I have driven all available routes multiple times and I concur with others that biking Highway 1 would be scary. Would you consider biking along highway 3 through the Crowsnest Pass? Its a much quieter road with less traffic and fewer elevation changes so I imagine it would make a nicer bike ride. I would recommend Highway 22 (The Cowboy Trail) from Calgary to the Pass, its a beautiful road, I have biked it and enjoyed it immensely.
Not the fastest, but I get to where I am going and enjoy it.