I’ve had kids of all ages on cruises. Teens enjoyed them the most, meeting others in the teen clubs and hanging out with new friends. Next best age were non-tweens, they liked the clubs. All 5 of my kids disliked tween clubs, on 2 different lines, including
DCL. I had a 19 and 20 year old on our last cruise, they made it work but missed the convenience of a dedicated area to meet up (most young adults are still traveling with parents on cruises, definitely not a college spring break vibe which they prefer).