GoGirlGolf,
There aren't a whole lot of highways across Canada. The primary (only?) one is the Trans Canada Highway, commonly called the TCH or Canada 1. If you're out of the cities, it's often a two-lane road for many miles. As long as there isn't any traffic, it's okay, but we much prefer U.S.-style interstates when our time is limited and we're trying to get from Point A to Point B. In 2006 we entered Canada at Sault Ste. Marie from Michigan and traveled east on the TCH to the Atlantic provinces. I have to say there wasn't a whole lot to see along the TCH. Unless you're in cities it's pretty flat with many miles of trees. If you go, be sure to get a Trailer Life Campground Directory so you can find places to stay. Distances are great and you need to plan ahead. Personally I would go across the upper U.S. on I-80 or I-90 and save some time which might better used, for example, around the Icefields Parkway, Banff, Lake Louise, the dinosaur areas, and other sights. You didn't say how much time you expect to spend on this trip, but if it's a "normal" summer vacation, you might want to rethink your routing and places to visit.
ArdraF