From Rome to Sorrento, it takes about 2 1/2 hours (245 KM) .
Take the motor-way direction Naples then follow direction “Penisola Sorrentina”, when you arrive in Castellamare (the exit after Pompei) follow always direction Sorrento.
From Rome, take the train Rome-Naples. From the train station in Naples take the train (Circumvesuviana line ) that runs quite frequently (approximately every 30 minutes from 5.00 to 22.30 ) from Naples to Sorrento. It takes about one hour, the cost is about Euro 3,50 per person.
From Rome, you can take the bus that leaves from Roma Stazione Tiburtina at 15.00 (only on workdays) and arrives in Sorrento at 18.45. (there is also a bus leaving at 7.00 a.m. only on Fry Saturday and Sunday)
To Sorrento there is also a bus, it takes about one hour the cost is approximately € 6,00 per person.
The timetable is
Naples Airport Departure: 09.00 11,30 13.00 14.30 16,30 19.00
From Sorrento Piazza Tasso to Naples Airport: 06.45 08,30 10.30 12.00 14.00 16.30