We are picking up a van at the Pisa airport on a Tuesday morning in April, planning on driving to Florence on Wednesday and returning the car to the Orvieto train station Thursday before going onto Rome. (Staying in Siena Tuesday and Wednesday night.) Knowing our time is limited (and we can't change that), please help me prioritize what Hill towns to visit and when. Plus, an idea of how much time to set aside to do so. We do have a couple of individuals who enjoy their wine, but it does not have to be a focus of the trip.
You should spend a half day each in San Gimignano and Volterra. They're both fantastic cities, with Volterra being the larger. They're also fairly close to each other. Orvieto is another of my favorite hill towns and it's 70 minutes by train north of Rome. The drive from Siena down to Orvieto is also very beautiful and very easy.
If at all possible, try to visit Civita di Bagnoregio which is southwest of Orvieto about a half hour. Check Civita out on Wikipedia--an incredible hill town dating back 2500 years.
Heather, please research ahead of time on where to park the car on the outskirts of the city of Florence in order to avoid the dreaded ZTL zone. If you enter this zone in Florence, you will get a very hefty ticket back in the States months, sometimes a year, later. Volterra is a lovely hilltown. Pick up the Rick Steves' tour book for a description of a walking tour through the town. As the previous poster mentioned, Orvieto is wonderful. If time allows, spend some time there after you drop off the car. Have a great trip.
Before you return the car in Orvieto, drive to Civita di Bagnoregio. Well technically you drive to the elevated walkway to Civita di Bafnoregio! (:>D
I'm confused. When are you going to spend time seeing Siena and Orvieto?