Florence Buses to Siena and Rome

You'd do best to visit Siena as a day trip by bus, as they take you into the city center. (Trains drop you on the edge of Siena.) Then go back into Florence to spend the night.
Then take a fast train from Florence into Rome Termini--with reservations. You can go online and purchase the tickets at a big discount up to 120 days ahead. From Rome, you take a frequent local commuter train the 20 miles down to Zagarolo.. I hope you have someone picking you up in Zagarolo, as the train station is maybe 3 miles from the town--across a deep ravine.

Zagarolo is where the Roman gladiators' trained in gymnasiums. The city's industry was making helmets for the Roman soldiers. Close by is a mountain with a fortress on top (Castel de San Pietro) and the pagan temple, Palestrina--another very interesting travel sight that's often overlooked by tourists visiting Rome. There are about as many travel sights in the Rome suburbs as there are in the city..

Thank you very much for the reply and the smart idea, but I've committed to a night in Siena. (Not nearly enough time, but in our next visit!) About the bus: would you know if I need to worry about the availability of bus tickets from Florence to Siena if I don't buy in advance? We have so little time in Siena that it would be a shame waiting in a bus station to get there.

And, then from Siena to Rome? I came across a Siena to Rome Flixbus, which has a clearer website. It leaves from the Siena train station.

Our Zagarolo accommodation is a 15-minute walk from the local train station, with the option to call for a shuttle should that ravine prove too steep. ; ). Thank you for the Zagarolo tips. I am tempted to wander the area rather than hurry into Rome every day.