It is about a 12 hour drive without stops or sightseeing from the Soo to Quebec City. The route crosses through some excellent scenery, and offers a lot of sightseeing, I would recommend taking at least a week to make the trip. I particularly like the trip from North Bay to Ottawa, which follows the Ottawa River for much of the way. We have stayed at a park in Mattawa a few times, here is their web site: http://www.sidturcottepark.com/
Ottawa, Montreal and Quebec City are each worth a few day visit. We have never stayed in Ottawa or Montreal as we have family there, but have used the following in Quebec City, and it is a PA Park: http://www.campingtransit.com/pages%20english/home/home.html
If you have time, the drive from Quebec City to the Gaspe Peninsula is one of the most picturesque and spectacular in North America.
Ed