We no longer rent a car in Europe. It has become too much of a hassel to find parking. If you don't have a GPS, the locals do not have a lot of patients with you trying to find your hotel. Trains are the way to go. It takes a little more planning, but alot less stress. 90% of the time, what you want to see will not be far from a train station. If you have to have a car for some sites, take a railpass that will have a few days of car rental.
Buses go to nearly every village and small town in Tuscany.
Your are right. A car is better for the countryside. However, taking a bus, train and boat has it advantages. In Croatia, taking the bus to Split and a boat from Korcula to Dubrovnik was very pleasent, and we met alot of nice locals and tourist. The only problem I ever had in Europe was the bus from the Plitvice National Park in Croatia. Buses are sporadic. No one knows what is the schedule. This would be a place where a car for a couple of days would be best.
Yes, Bob, but there are 3 different companies running buses and they don't coordinate their schedules. It is pretty hard to see more than one town in a day by bus and can entail much waiting time at remote bus stop for a connection.