Where are you planning to travel in Canada and the US? Youth Hostels can be great accommodation, you are right. Whether many of them are practical depends on how you plan to travel. If you will have a car there are great YH in rural areas. I have found that some of the hostels in urban areas are a bit rough. Let me qualify that by saying I have not been to many urban YH. If you let us know where you plan to travel I am sure someone will be happy to help you with specifics.

Enjoy your trip. Jude