Taking the Italian TWHS discussion to where it belongs.
Giardini Botanici Hambury
Island of Asinara
Lake Maggiore and Lake D'Orta
Pelagos: The Cetacean Sanctuary
The Aniene valley and Villa Gregoriana in Tivoli
The Marble Basin of Carrara (I met the guy who drove around with the stunt guy from the Jamese Bond movie...what a connection indeed!)
The Prosecco Hills of Conegliano and Valdobbiadene (actually the mountains nearby are worth a look instead in summer)
Via Appia "Regina Viarum" (probably impossible to miss if you go to the tombs in Rome anyway)
If normal standards applied to Italy they should just go for the full country inscription and be done with it. There are so many historic and nice places. My personal favorite is Bobbio. But to me Italian sites have to be better.
In your list I find several sites where I would disagree:
* Prosecco Hills are a joke, especially when comparing them to the Champagne.
* Neither Bologna nor Pavia entice me much.
* Bergamo is effectively inscribed via the Venetian works of Defense.
* Clydes review of Parma is fairly lackluster. Having travelled in the area frequently, it's not that recommeded.
Places I enjoyed:
* Lago d'Orta and Maggiore.
Places I would be keen to visit: