We are traveling from Siena to Sorrento. In previous visits to Sorrento we have taken the Hydro. Another poster suggested a train. I could not locate train information for this, but was also wondering time/ cost basis.
This is the quickest and easiest connection showing on the current timetable.
RE 3032
Dep 08:47 SIENA (Italy)
Arr 10:05 FIRENZE S.M.N. (Italy)
FR 9563
Dep 10:24 FIRENZE S.M.N. (Italy)
Arr 12:53 NAPOLI CENTRALE (Italy)
Buy your Freccia ticket, for Florence to Naples, through trenitalia as soon they become available. The local Circumvesuviana will get you from Naples to Sorrento.
The Circumvesuviana runs from Napoli Centrale lower level to Sorrento, about every half hour, takes about an hour to arrive.