We've done this one in a couple different configurations over the years.
We were just in Grand Turk right after Halloween. It is a beach/big as heck pool right at the port, just steps away from the ship. Pool is included, I take ice water and I can make it a zero cost day (I don't drink but there are plenty of Margaritaville drinks and you don't even have to get out of the pool). There is a for cost flow rider, it was not working in November likely due to the hurricane. And if you get too far away from the ship there are vendors that will charge for chair. Remedy that by walking to Jack's Shack or staying in front of the pool. Its a small island. We didn't find the golf cart tour as worthwhile as I had hoped. Honestly, the pool is the best deal at GT.
Bonaire will be new for us in just 35 days. I have a golf cart reserved. My main goal is to snorkel and see the salt and maybe a flamingo for a bonus.
Aruba is a bit like Cozumel with the desert thrown in as opposed to the jungle. As far as you can do pretty much any type of excursion you might desire. Its relatively safe. There are resorts that sell day passes and every kind of tour from trikes to side by side's to a party bus or a non party bus. Casinos. Safe shopping. Beautiful beaches. We like to visit the grocery store, its close/walking distance and we always like to see different ones in different countries. Our personal favorite is snorkeling with Aruba Bob at Mangel Halto but its become very pricey and one of us has stopped snorkeling due to age. He goes to the casinos now.
The Magic will be between the Spirit/Legend and Panorama in size. Easy to navigate, still has the glass elevators and old style atrium. We sailed her in 2017 and again in just a few weeks. I do have the Spa/Relaxation booked and I'm looking forward to the Thalassotherapy pool. It has a nice view. She has a bit of the old fancy elegance that you saw on Legend upped with a ton of neon. They did away with it by the Breeze and went with Caribbean theme.