I did a 3300 mile euro trip over 2 and a half weeks a couple of years back :)
Managed to fit in the stelvio pass and the surrounding areas, as has been said the stelvio is full of coaches and cyclists and its a struggle to do any 'real' driving on it imo, I found the surrounding roads in particular the davos to bormio road much better tbh
Just book your own accommodation and route, adds to the fun and allows greater autonomy over what you do and when imo...
We did home to the nurburgring, couple of days there then down to Baden Baden, then south to lake constance (freidrichshafen), Lindau, then into davos in Switzerland..
Stopped off at mount santis then over towards the stelvio, then back down into Austria via Italy.. Back up into Germany to Ingolstadt and a tour round the Audi factory, then over to Leipzig for the porsche one...
Then over to Wolfsburg for the vw factory and autosdtadt for a few days, then a stop in Munster, over to the Netherlands and the ferry home..
We actually changed our plans re accommodation using an iPhone and booking.com on route as we decided to go a different way a couple of times, added to the sense of adventure greatly