Hi Guys I'm in planning stages

Hi Gareth, your outbound route is one I've taken many times and is the most efficient and interesting option. We usually aim to get to Calais for late afternoon/early evening and put in 2 or 3 hours before stopping over in St. Quentin or Reims. This takes care of the most boring stretch and gives you the whole following day to complete the journey to Italy at a reasonable pace allowing for breaks and refuelling etc. The rest depends on how much time you have but I would recommend taking in Lugano and the its lake after you exit the tunnel and arrive in the Italian part of Switzerland prior to crossing into Italy proper. Unfortunately I've not had the opportunity to travel back across Austria as yet but have come via Germany, and bits of Belgium, France and Luxembourg (accidentally) taking in 5 countries by car in a single day! It can be fun and I'm sure the scenery through the mountains will be fantastic. If you have the time and can treat the journey as part of your holiday (planning your stops carefully) you shouldn't have any problem.   I hope that's of some help to you,. Buon viaggio! 

If you want cheap petrol - go Calais,  dunkirk, Lille, [if short of petrol, there is a Le Clerk superstor/petrol place just off motorway before Lille,] Namur, Luxembourg, Metz - all good motorways and no tolls.  petrol in Luxembourg is cheapest on your trip.  Did this route 3 weeks ago  [only marginally longer than yours with, but no delays for toll booths]You could then do Metz - Strasbourg as per your post, or [for free] Metz Nancy then Mulhouse or Colmar.  Last bits are not dual carriageway, but are good roads over the mountains - no problems there.I always avoid Basle.  Mulhouse on to German autobahn get the Vignette for Swiss motorway at first services you get to, then take the motorway to Lorrach - this avoids Basle and its traffic/delays.  Straight into Switzerland and on to Gottard Tunnel Other option is Calais - Rheims, Dijon Besancon and into Switzerland that way, then around Lake Geneva and into Italy via the Simplon pass - nice easy route [my route with the Doggie on board].     Quicker, but tolls are paid in France