Florence to Siena to Assisi Public transportation recommendations

Train, train, train -- just like the same question in your other posting. Roughly four to five hours with 2 to 4 train changes almost all on regional trains.

From Florence to Siena, I believe bus is faster and goes to the center of the city, rather than to the bottom of the hill outside of the city where the train goes. Rick's guide has very good info on transportation between cities.

Florence-Siena. Tiemme spa bus. # 131R 1:17m

Siena-Assisi Flix bus, 2 a day @ 8:40 & 18:00 1:55m.

The 131R bus is possibly faster than the train, the regular 131 bus line is slower since it makes many more stops.
I think both bus lines stop in the city center, but I'm not 100% sure.

Florence to Assisi:
Direct with FlixBus: 2hours1/2 twice a day
11:50-14:20
17:10-19:40

With train you have stops and it is much longer, check with Trainline EU app.

For Siena, there are direct trains but Siena train station is not in the centre
and Siena is hilly. With the train it takes you 1h1/4

With the bus from the Florence central bus station or from Porta Romana the bus takes you right to the centre but it is a little longer maybe 20 minutes more.
when taking the bus, make sure you take the direct bus.

Last year we took the bus from Florence to Siena. Florence bus station is near SMN train station. Bus drops you off in Siena near Piazza Gramsci. You can walk up to the square and get a taxi to your hotel.