What is the best train station to use in Rome for trains coming from Florence?
Roma Termini is most central and where fast trains arrive
Termini, the main train station on a direct Frecciarosa train with no stops.
The best station is the station that's closer to your hotel.
Trenitalia's and Italotreno's High speed trains to Florence call first at Roma Termini and then stop at Roma Tiburtina station.
If, as an example, you were staying close to Roma Trastevere station you could take a slow train to either Termini or Tiburtina and transfer into the train to Florence.
Transfers at Termini are easier with luggage, but Tiburtina is smaller and less crowded.