From what I gather on the Looper message board, Georgian Bay's North Channel (which we haven't done yet), the Trent Severn, Rideau, Chambly, Lake Champlain and Erie Canal are the best part of the "Great Loop". PLUS, it's very economical cruising. The Erie Canal is mostly FREE once you pay the $75 season pass for the locks. The Canadian canal season pass was around $700 which included the locks and docks in the entire Parks Canada system. I consider it a good deal. Canadian fuel is high, though. We managed to avoid fueling by the litre, though.
Speaking of locks, we did 158. That feels like an accomplishment.
Six weeks for us is a comfortable amount of time on the boat away from home. After 30 days of not paying bills, they start to go to collection.
Since we were in the area, we thought of continuing on with the Down East Loop or heading down the Hudson to the Chesapeake, but family plans dictated otherwise.
We love rivers, bays, and canals. Open water for us is just to get there, though we have had nice times on our crossings.
If you're thinking of cruising any of these waterways, feel free to contact me with any specific questions. I'd love to help you plan your trip.
John