Day Trip to Napoli?

First of all from Sicily to Rome you should fly instead of taking the train which takes forever and a week. There are plenty of options from the 3 main Sicilian airports and all of them are Low Cost, except for Alitalia: Palermo PMO (EasyJet, Alitalia, Blue Panorama) to Rome FCO Catania CTA* (Blue Panorama, Meridiana) to Rome FCO
Trapani TPS (Ryanair) to Rome CIA. * Note that CTA is under renovation and flights are temporarily operating from the NATO Naval Air Base of nearby Sigonella (NSY). By the time you go, CTA may be reopened. Once in Rome you can certainly do a day trip to Naples, which by train is only just over 1 hour away. Besides la Bella Napoli itself, you could even visit Pompeii. From the Napoli C.le station, just take the Circumvesuviana commuter train and in less than one hour you'll be inside the Pompeii archeological site.

Ross, As you're going to have five days in Rome, a day trip to Naples is a great idea! Is there anything in particular you're interested in seeing there? I would definitely recommend the Archeological Museum, especially if you're also planning to visit Pompeii. Of course, having a genuine Neopolitan Pizza in the place where it was invented would also be good. I also enjoyed seeing the Veiled Christ in Cappella Sansevero (Via Francesco De Sanctis 19/21). Whether or not to also visit Pompeii or Ercolano will depend on how much interest you have in those sites. Visiting both Naples and Pompeii in one day will be a LONG and probably tiring day, and of course that will reduce the time you have to spend in Naples. If you happen to be in the area and have a few minutes, be sure to stop at Caffe Gambrinus for fantastic pastries, coffee or perhaps some Limoncello. Although I'm sure you're already aware of this, be sure to wear a Money Belt, as the pickpockets in Naples are very good. You might enjoy watching THIS VIDEO of some of the tactics used by pickpockets in Naples (it's a 45 minute video). Happy travels!

Yep, @Ken, always wear the neck wallet (more of a neck wallet than a money belt guy). That's one reason to head to Rome first and put the bag and banjo in the room and just day trip to Naples. Realize that flight would be faster but I'm also a train guy. The speed of the trip to Rome from Palermo is not the primary consideration. Thanks guys!

Ross, if you have five open days that you can switch to your time right after Sicily and want to take the train, you can stop in Tropea, a seaside town hanging onto a cliff, head north to Paestum (Greek temples, good museum, beach which will not interest you in Feb/Mar but you'll have it to yourself, and mozzarella farms you can visit), spend some time in Sorrento/Amalfi Coast, and then take the Circumvesuviana from Sorrento to Naples. The Circumvesuviana will stop downstairs from the central station in Naples, you can leave your luggage at the train terminal, have a good day in Naples and then to Rome. Otherwise, Roberto's advice to fly (you can fly from Catania or Palermo) will work better than the hours on a train (which can be delayed - one train trip from Messina to Rome took 13 hours!).

Robertos suggestion is a good one. However consider staying/visit in Sorrento after Naples and see the amalfi coast. It is an incredibly beautiful coast line/villages with vistas travelers dream of. It is stunning!!!
You could also ferry from Naples to Sorrento, WOW.