I almost think you need to rent a car for at least a portion of the trip, especially if you are staying outside a major city. Siena, Florence, Rome all obviously have transportation, so no vehicle needed, but if staying at Spaltenna, you need something. Its about 45 mins from Spaltenna to Siena and over an hour to Florence. But, the ride from Siena to Spaltenna is one that can make you blow chunks, at night its dark and curvy like crazy. After dinner at Sotto Le Fonte, Britta has called a cab for friends, so I suspect you can taxi to Spaltenna. My best advise, if staying at Spaltenna first, is to grab a car at FCO and drive there. Up the A1 it should be about 2.5 hours I think. If you arrive at 7a remember, car rentals open at 7a exactly. So, if you are early, they wont be open. But arriving at 7a gives you plenty of time to enjoy the ride and maybe make a side trip on the way up. Orvieto is along the A1 and worthy of time. Along the route there are numerous AutoChefs and ChefExpresses, basically restaurant/bars within gas stations off the highway as you head outside of Rome going North. You can stop, go in for a pastry and coffee or two and zip back up. I always rent from www.autoeuropa.it Make sure its not .com and not autoeurope. AutoEuropa has great automatic vehicles and I've never had a rental issue. Use the car while at Spaltenna then you can drop it off at the Florence airport and take a taxi into Florence. Then go public in Florence and Rome. You can drive from Spaltenna to all your hidden destinations, maybe even get Assisi on the menu. Perugia is nice and has the Perugina chocolate factory there too for tours. From Spaltenna to Siena, you could hire a tour driver for the day and make sure they drive you to tour Siena and stay the evening while you have dinner. Just some random ideas. I like seeing you have Avignonesi on the schedule. The tour and lunch is amazing.