"Any other suggestions regarding renting a car in Italy?"
As mentioned in a previous reply, it would be a really good idea for each driver to obtain an International Driver's Permit, which is used in conjunction with your home D.L. Many rental firms are asking for an IDP these days, and it's compulsory for driving in Italy. These are easily obtained at any AAA/CAA office for a small fee.
Also as mentioned, you'll have to be extremely vigilant to avoid the ZTL (limited traffic) zones which exist in many towns and cities in Italy. Each pass through them will result in hefty fines, which you may not know about until several months after you return home. It's NOT a good idea to drive in Florence, as the city is well covered with automated ZTL cameras.
In most cases, I find that the high speed trains are the easiest way to get around Italy, as that's a more efficient use of my limited travel time. I tend to use cars to reach places that aren't well served by regular public transit.