Sayhello, do you have any other recommendations? Norway was a good fit. Son is 8. Not looking for too much physical or too much museum at his age. That was the appeal of Amalfi. Was also interested in Japan. Big trip, and would have to add disney sea, at least, while there.
I don't have kids, so I can't really talk from that point of view (and I haven't done Norway, though it's high on the list).
Japan is an *amazing* itinerary. You know your son best on whether he'd be good with such a long flight or not. Hopefully someone who has done this trip with kids will chime in. It's not as temple/shrine heavy as it used to be, and has some cool activities (sushi making, Kintsugi, and the fabulous Taiko drumming activity). And it's not a very physical trip. Make sure you are looking at the new itinerary for 2025. For some reason they still have the 2024 itinerary coming up as the default on the website, and they have made some changes recently (I think most of them are good changes).
Iceland is also a very cool trip (pun intended). Fascinating natural features, some good hiking, some physical stuff but not a lot.
Scotland is also a fabulous place, although the itinerary is totally different from when I took it. But it's still a great itinerary.
Greece is a fascinating place, and it's a great itinerary. Not too much in the way of museums, although a lot of history. A nice amount of physical.
London/Paris is probably too much museums (but again, I don't have kids).
Lots of people really love the Costa Rica trip, but that is a pretty physical trip. (I haven't done it).
I've heard good things about the Ireland trip, too. (You stay in a castle for part of it).
Anyways, hopefully somebody with kids can chime in on which one sounds best for your son.
Sayhello
There are so many other fabulous trips to choose from, and I don't think the Amalfi trip is going anywhere. 
