When you get off the inter-city train at Napoli Centrale, look for signs for the "Ferrovia Circumvesuviana"--it is technically part of the Naples rapid transit system. I think that there are technically five different terminals in the Napoli Centrale complex. It's not that hard to find.

What it is is a narrow gauge railway that goes past Ercolano (Herculaneum) and Pompeii, and the end of the line is Sorrento--about 30 miles south of Naples. I was last on it in 2003--it takes an hour, and I think you can buy an all day pass on this train for less than E10.00 per person. As there were no hotels immediately around the terminal in Sorrento, you'll want to catch a cab to your hotel.

This is one of the most colorful rapid transit trips in the world--you will encounter street musicians and street theater on board the train, as they go from car to car seeking coins from the riders for their performances.

As for Rome, my family stays at the Tiziano, located on the Corso Vittorio Emanuele II, about half-way between Termini railroad station and the Vatican. Bus #64 (and a number of others) depart from in front of Termini and stop across the street from the hotel, which is adjacent to a block of Roman ruins called the Largo Argentina. The Pantheon is just a couple of blocks away, as is the Campo dei Fiore (flower market square)--Piazza Navona is not much further--around the corner from the hotel is the terminus of streetcar (tramvia) #8, which will take you to Trastevere. Between late September and early May the top two floors of the Tiziano are occupied by the Saint Mary's College (Notre Dame, IN) Rome program, arguably the best of its kind (my wife, her sister and my daughter, all SMC alumnae, were on this program).