You don't state how long you are intending to sail, but assuming it's only 2-3 weeks, I'd say you have the choice of circumnavigating Sardinia (west and south coast interesting,
east coast less so, with the exception of the jewel of the Maddalena Islands) or cruising between Tuscany, the Tuscan islands and maybe even the NE coast of Corsica). Unless you want to spend a fair bit of time ashore (e.g Pompeii, Vesuvius etc), there's not much good sailing around Naples. If I were doing it, I'd
cruise from the Tuscan coast to Elba (several nice harbours), down to Giglio (once the media scrum has left!), then across to
Corsica, winding up in Bastia before crossing back to the mainland.
Details on all the islands and harbours are on the World Cruising Wiki (see link at top of page). Of course, you'll find everywhere packed if you go in high season and will have to arrive early to be sure of a berth. May, first half of June and September are usually the best months for the right combination of
weather and lack of crowds.