I pondered this a few years ago, on a cruise that was ultimately cancelled due to COVID. We chose Alaska because of the Ovation of the Seas - seemingly more wow for the kids. The Norway itinerary was perhaps the Serenade of the Seas - still a great ship, but seemingly less kid friendly. Also know the Alaska ports are more touristy, but they seemed more accessible for kids. Can't go wrong either way, though. I was on the fence, too.\
Total aside, but we are using our COVID cruise credits to sail on Odyssey in August. Europe is amazing, though a different climate/dynamic between Norway and the Greek Isles.