Well, on St. Maarten, take the launch to Anguilla and swim with dolphins!! This is a life changing event!! It is a bit expensive, but it is so very worth it! My wife, our children, and I absolutely LOVED it!! And the beach you go to after is absolutely breathtaking!
On St. Thomas, you must visit Blackbears's Castle! Then shopping downtown is the thing to do! That's where my lovely wife will be when we go this October! Me, I'll be partaking of the rum!
Oh, and don't forget to save some shopping money for the outdoor bazzar! It's where you can really barter with the merchants!
By the way, you will LOVE the Magic! Slightly different decor in the Atrium! Mickey instead of Ariel, and Lumiere's instead of Triton's! But trust me, after sailing on the Wonder for your 4 day cruise, you will feel like you are "home" when you enter the Magic!!
And as for that "far away" feeling you have right now, the time goes very fast! We booked our cruise last July, and we said the same thing! We thought 15 months away is FOREVER!! But now it's only 2 months away!