three weeks is likely harder to plan than three days! Italy is chock full of fascinating places - so your interests will dictate most of where you go and what you do. one tip - most of the "ruins" / sights offer only limited access to "walk thru the door buy a ticket" tourists. for $30-$50 per "joint" you can get officially licensed tour guides than have much more 'thorough' access to many more areas, plus you get to learn what it is your looking at.
hiring out a villa and a private chef probably doesn't qualify as "tourist" - but it's certain on the high end of isolation. my own styles is more like "Heh, the guy's digging potatoes, let's go talk to him!" but everyone has their own thing to be done.
the best meals I've had in Italy is where Momm's covered in flour in the back and the cats are begging at your table, and you sit there wondering if the car's gonna' get sideswiped.
I take a car, don't bother with reservations, and go wandering. you will need reservations for the big places - Rome, Venice, etc., especially in high season. oh, take the collision/etc insurance on the car - if you think northern/NJ=NYkers drive crazy, you've not seen nuttin.
(hotel venice Orion 041-52-230-53 - right off St Marks Sq - two star hotel, five star people)
I'd fly to Munich, rent a car, drive thru the Dolomites - Venice - <bunches of close places> - south to Bari
cross the spine, up to Pompeii, thence Rome (Rome - can take a full week),
thence west to Torino/Aosti/Piedmont, over the Alp high road into Switzerland and back to Munich to fly out.
there are issues with full dependence on air in and out of Italy. somebody gets mad, there's a strike.
also, never return a rental car in Italy. the return location(s) have a habit of changing your contract, usually involving multiple hundreds of dollars in mysteriously new and unannounced / undisclosed "fees"  |