Never too late to plan/book, though some of us love the research so much that we'd always want longer so we can dig into what's there for us to enjoy on arrival.
Perhaps the easiest way to start, is to look at direct flights that have reasonable timings, and narrow them down to 3-4 that might have some appeal. Nice also to have a city vs. countryside/coast/mountains comparison between 2 destinations, so the 2nd leg feels a very different experience.
I like Amsterdam as a city, but less so the centre, which struggles a little with tourism and the 'type' of tourism. They're working on addressing this, but my tip would be to stay outside the centre (we like the area beyond the museum quarter, which is relatively 'leafy' for Amsterdam, and very much a place for Amsterdammers more than tourists). The centre is vibrant though, if that's an appeal, and of course even if staying outside, you'll want a few trips into the centre / other suburbs.
Another very useful side to Amsterdam as an airport, is the massive range of destinations it connects to. Thus it makes it a useful option for a 'triangle' so you fly into Amsterdam, but out of (say) Pisa. Now normally I prefer to avoid flying in the middle of the holiday, but it may work brilliantly for you.
Having been to the south of Italy, perhaps the North might appeal? If you like food, Bologna is pretty special, though not overly scenic around it. Tuscany/Toscana can be very scenic indeed and with lots of options from the obvious like Florence/Firenze and Pisa, through to some relatively under the radar places like Colle val d'Elsa or Lucca. Milano remains a fashion/style hotspot, though the city didn't gel with me. Torino is a favourite, albeit in comparison to Milano might feel more mundane, but the food is great and navigation easy. The lakes (Maggiore, Orta, Garda) should be very nice at that time of year. Then again, if wanting peaceful and beautiful scenery, with some wonderful walking, you might say "sorry North, the Amalfi coast is calling"
