We have a blast on our family cruises, and we end up spending less than we do when we do a land vacay. If you like beach time, an itinerary that includes Half Moon Cay or whatever private island the cruiseline offers would be a good choice.
Also, some of the larger ships have awesome waterslide areas. If you are taking young kids, our grands loved Camp Ocean. Our five year old grandson is normally shy and doesn't do well with new experiences at first. He actually begged to go to Camp whether the others were going or not.
Most of the adults in our family enjoy the spa, so you might want to check into spa passes or even spa cabins if budget allows. Personally, I would rather go to the dentist than the spa
Check out YouTube videos of ships you are considering.
Also, make sure everyone understands exactly what is needed in the way of passports, birth certificates, etc, and be sure they know to read the cruise contract so there are no surprises.
Good luck, and I hope you get your wish :)