This itinerary from Galveston to San Juan on the Magic?
If so, fun, different, itinerary.
First off, two beach days. Just consider them as that. The water in the Bahamas is beautiful. You will have loungers and umbrellas set up and waiting. Pick up towels as you leave the ship. They will have a 2-hour window for lunch. It’s nothing to write home about, but it’ll do. You’re eating again soon, anyway. It is an opportunity to enjoy the sand, water, and sun. There is a stingray activity CC. Some boating activities. There are no water park activities or pools. Just Pelican Plunge at CC - a set of slides into the water, reached by swimming to the feature. And some snorkeling in a protected area.
Nassau is a port with which cruisers have a love it or leave mentality. A lot of guests do stay onboard. But they have done an overhaul of the port area, so at least a walk around the enclosed portion would be a reason to get off. There are resorts with big water parks; I have twice been to the Atlantis for theirs. Baja Bay is fairly new (requires transportation), as is the smaller one at Margaritaville (walkable). And other options.
The ship seems to offer more activities in Nassau than they did in the past. Check out that day in particular when looking at old Personal Navigators.
The three Sea Days will be able to give you a taste of onboard activities.
There is a lot less walking and standing for anything on a Disney cruise. And less organizing your days. No dining plans to be made.
If you are in the Magic, Rapunzel should come to your table for a visit; later, there is a little show. Animator’s Palate has walls that share a story (musical accompaniment, of course). Triton’s/Lumiere’s is a good night to dress pretty, as it has a more formal, palace setting.
There is lots of character meets - and some seen in the wild.
My lesson from disembarking from San Juan: stay overnight. Nearly any flight you can get will be in the afternoon. You disembark in the morning and then sit around the airport with more people than chairs (it seems). If you leave the following morning, you can get an entire day of sightseeing. Old San Juan is historical and charming. Easy to do on your own. Or go in a tour to El Yunque, the rainforest.
It is like a floating Disney hotel with added activities and port stops. Food is available around the clock (room service is included. Mickey bars in the Main Dining Rooms). No having to budget for food.
The bedding is luxurious.
Whether it’s this itinerary or another, if you enjoy your family, it can be fun.
Hope you enjoy it as I much as I did just writing about it.