The wife and I did Italy 2 years ago. We started in Rome (4 days), on to Tuscany (5 days), up to Italian riviera (3 days) then over to Venice (3 days). I loved it all, the food, the history, the culture. Favorites in order... Rome (have lunch with the Pantheon as your backdrop...unbeatable!). Italian riviera. Stayed in Rapallo, hop the train to Cinque Terra and hike the trail between the five hill towns. Amazing views and friendly people. Venice...splurge and have lunch at the restaurant atop the Hotel Danieli overlooking the grand canal. Tuscany...did not need 5 days here, while beautiful and relaxing, I would have enjoyed having an extra day in Rome or the riviera. Obviously Florence and Siena and good stops in Tuscany, but also try to hit one of the smaller hill towns (San Gimignano was very cute).
I agree Cinque Terre is great and worth a trip. We spend a lot of time in Northern Italy around the lakes. I´d be in heaven if there were a Marriott option up there. you can take a train to Lake Como if you feel so inspired.
Venice is unique in the amount of people that cram in there. It´s super cool and I love it, but be prepared for a ton of people.
If you go to Florence and expect to visit the Uffizi, you´ll need to buy tickets ahead of time with a reservation time, Especially in the summer, which goes on well into Sept.
I like the freedom of driving in Italy, but if narrow roads make you nervous and most likely a stick shift, trains might be the way to go. I have to say, as much as I love it, I have dropped some seriously inappropriate language driving on some of the winding roads and having buses coming the other way.
sounds like a blast. This is our first year in a while we aren´t going. I always have a bit of regret not going when I hear about other´s trips there. enjoy! It´s such a lovely country.