It does really depend on where you are heading in Italy. If its in the direction of Lake Garda/Venice then perhaps Germany/Austria/Italy is the way we generally go. Tolls on Italian Motorways tend to be a bit cheaper than in France so I suggest you reconsider. Some of the SS roads (super strada) can be a bit potholed.
The last time we went to Italy we went from Calais via Luxembourg, Nancy, the Vosges, Colmar, Lake Constance, and the Austrian Tirol - just because those were the places where we wanted to spend a few days on the way. The previous time we went into Italy in summer via France and over the Mont Cenis Pass because we like that part of the Alps. Other people have their own favourites I'm sure.
Big fold out paper maps and felt pens are still useful for route planning
Don't forget to leave a review of the French and other European campsites you have visited!