I've got a trip to northern Italy planned for early June so was really interested to see your northern Italy route but it turns out it's all the places I'm not going!!
My route is to get from Folkestone to Basel in the first day and then head through the Dolomites (including Stelvio) and on to Lake Garda, Venice, Florence, on to the coast and then back up to Switzerland (Geneva/Lausanne), maybe stopping in Dijon and Reims on the way home...should be awesome!