Hi Hilarion,
I'll be on a part of your itinerary - I'm onboard from 17th Jan until 24th Jan.
I've been on a few MSC cruises before, and I had some taste of NCL. There's definitely a difference between them, and if you're curious about anything in particular, I'll try my best to answer.
I don't have anything in particular planned for my trip. I'm taking it to relax after an intense college course, and am looking forward to just relaxing with a book somewhere on the ship.
In terms of excursions, there's a few interesting options and I'm sure you'll find something that interests you.
Unfortunately, I know little about what to do in Sicily, but when I was looking at what to do in Messina, the hop on-hop off bus routes are looking interesting - there is one that goes around the city, and there is one that goes north towards a nice beach. Maybe that's something you'd be interested in.