If you get on the section South of 18 mile island below Wolesley Bay you can get away from the heavy motor boat traffic.
Try the routes and trip logs for the French at this most excellent website:
http://canadiancanoeroutes.com/
or get a copy of Toni Hartings book. French River- Canoeing the River of the Stick Wavers.
If you get down to the delta (near Georgian Bay) make sure you have good navigation skills as it can be a bit confusing I'm told.
Have a good trip.
John