Siena to Rome bus - and transfer to hotel

If I were going to Rome from Siena, Siena would be the last place where I would drop the car.

My first choice would be to drop it at an office at the Tiburtina station, which is very easy to reach, just off the freeway from the tangenziale Est (A24). Then from there I would get a taxi to my hotel in Rome.

If you don't feel comfortable leaving luggage in the car in Orvieto, where do you plan to have your luggage if you drop off the car in Siena? Orvieto has no luggage storage at the station.

Roma Tiburtina is a good distance from Piazza Navona and the area around the station is not difficult to navigate. It would probably be the most convenient place to drop the car.

Twenty minutes is a good amount of time to transfer trains, even if you have to use the sottopassaggio.

Rick's book mentions 9 - 10 buses/day between Siena and Rome, which I understood to be direct buses. This Baltour schedule confirms that.

Marie,
I don't understand the problem.
If you want to avoid driving take the bus from Siena to Rome, Laura gave you the link, this is the least hassle.
If you want to take the train, Chiusi is a small station no problems navigating. You could go to either Tiburina or termini.
You could drive to Chiusi. There is a Hertz within 100 meters of the station.

Thank you.

I believe I must have been looking at the wrong schedule, as the linked bus schedule, which is direct, looks great.

We are picking up a car in Venice - driving down to Siena, and spending a few days in the Tuscany area. I thought it would be easy just to drop the car back off in Siena, and then take our luggage on the bus to Rome. And since it now seems as it is a direct shot to Rome, then it's much more straight forward.

Personally, I would rather drive. The cost is about the same to keep the car the extra "day" (or few hours) as it would be to be to take the bus for 5 people. But my husband thinks the drive from Siena from Rome might be hectic, which it appears not to be according to these posts. In either case, we will have to get a cab to take us to our hotel.

I think it's smarter to pick up the car in Venice and drive to Siena, unless someone thinks that isn't a good idea? The train from Venice to Siena is a bit more costly.

Driving to Rome is not hectic as long as you don't arrive during the morning commute. Just time it to be there in the late morning or very early afternoon. To avoid the GRA traffic take the A1 toward Naples, then exit at ROMA EST (A24). Follow the directions to Roma Est/Roma Centro (target symbol). Put some gas along that last stretch. The freeway ends after the under pass, right at the Tiburtina station. It can't be any easier. And I would stop in Orvieto along the way. They have a guarded garage (just put suitcases in the trunk and back the car against a wall so that they can't open the trunk.
To convince your husband to drive, just tell him a real man would drive into Rome. That will challenge his virility enough to convince him to drive and show you how manly he is. Besides someone from San Francisco shouldn't be afraid to drive the 7 hills of Rome. To get used to the traffic in Rome, just drive around Market street during commute hours when there is a game at the AT&T park and the critical mass bikers are in town. That's Rome at commute time.