What an amazing thread.

I consider Naples one of the most underrated cities not only in Italy, but in the world.
It is nowhere close the level of tourism (quantity and quality) it deserves, and I kept thinking this from a double vantage point: not living in Naples itself but close enough, and having 95 countries visited behing me and counting.

The city is overwelming, slowly captivating, definitely flavourful. I'd say charismatic.

It's Italy and its stereotypes on steroids, love it or hate it.

My idea is the pedestrianization of Lungomare di via Partenope and via Caracciolo was a game changer: visitors were given a safe, livable and panoramic part of the city to hang and leisurely stroll. And this is what a tourist want.
The airport is growing at a steady pace, destinations increase and the incoming Ryanair operations from March will likely perform another shift forward.

The direct connection with the metro from airport to city center, railway stations (Centrale and Garibaldi) and port on the same line will be another kick, once ready.

Additionally Naples is incredibly inexpensive, even for extra Europe standards.
Basic salaries are so low that the official and unofficial economy had to cope with it.

I'm not sure the average tourist stays in Naples more than Venice or Milan. The city has tons of cruise ships and most of them anchor in the harbor not even a full day, and mostly in summer.

Recently the popular RAI science and history TV program "Ulisse: il piacere della scoperta", aired an episode dedicated to Naples.
It's worth watching, though is only in Italian. A vpn is necessary from abroad:

http://www.raiplay.it/video/2016/11/...a8ba57c46.html