If you were visiting europe what would you see?

[pilninggas]

Could a campervan be an option?

OP: If you can do a bike (and lots of us tour Europe and further alone riding into the heart of a great city and parking for free is not to be underestimated.), buy a camper van - a decent one - use it and sell it when you are done. You'll get your money back, unlike a hire car, and if you catch the bug you can keep it. You can still hotel, you can stay in the laybys and aires or in campsites.

All routes, particularly non motorcycle will hve compromises. But Como to Bolzano then the back roads to venice is a million times better than Milan to Venice on the Autostrada - it's pretty industrial on that route anyway.