Hi Sylvs,
I did this tour in 2011, in September, and had a brilliant time - the Alaska add on was part of that tour, but to my knowledge that bit doesn't happen anymore. The Canadians are lovely people, and the tour guides and coach drivers all seem to be excellent - we had Allison as our tour manager (totally off her rocker, and fantastic fun!) and Jason was the tour guide/driver and he was hilarious.
You would have a fantastic time and I would say go on as many optional tours as you can - rafting, glaciers, helicopter rides - the lot!
Best wishes
Anne