Before offering any suggestions on an Itinerary, it would help to know the time frame of your trip? That will have some bearing on what type of transportation to use. How long do you have to "tour the country"?
Also, as you're "excited nubies", I'd highly recommend pre-reading the Guidebook Europe Through The Back Door, as it will provide lots of tips on things like Itinerary planning, transportation, language issues, money, etc.
Generally speaking, I usually prefer travel by train as it's much faster and a more efficient way to get around. A few things to keep in mind are that for driving in Italy, each driver must have the compulsory International Driver's Permit. Failure to produce one can result in fines on the spot! The others have mentioned the aspect of ZTL areas (Zona Traffico Limitato) and driving through one of the automated Cameras results in a €100+ ticket EACH TIME. A GPS unit along with a good Map would also be a really good idea.
A few more points to note - some countries require a mandatory "highway permit" (Switzerland among others) and car rental firms usually charge a huge fee to rent a car in one country and drop-off in another. Using open jaw flights would be the best choice, so where to drop the car will be something to consider.
The best advice I can offer is not to try and see everything in one visit. Choose sights carefully and allow adequate time for travel between locations. As Rick often says "assume you will return".