The Canadian is a great trip. I go once a year. Dome cars all year. Train is longer in the summer, shorter in the winter.
Winter offers the best price and the best view, as the leaves are off the trees and you can see far. the days are shorter, but the view is great.
trip from Vancouver/Toronto or Toronto/Vancouver takes about 4 days. Check VIA for the scheduled times. From Toronto you can take an Amtrak day trip to New York City, where you can connect for a return trip with many routes.
there is also dome cars on the Skeena (Jasper to Prince Rupert on the coast), and Montreal to East Coast in the summer (no dome in the winter).
Good advice to sign up for special fare notices, as the prices can very and it is hard to randomly check the VIA web site and get the best rates.
You will love the trip, as these are the original Budd cars, which have been refurbished on the inside a number of times. the outsides are original and may never wear out.
this is a 5 star hotel on wheels. great service, but not cheap.
Enjoy your trip: Joe K