I have to say that is probably one of my favorite caribbean itineraries and I would definately choose the Nieuw Statendam vs. the Nieuw Amsterdam simply because its one of their newest ships.....I think this ship would serve you all best. I have sailed the Nieuw Amsterdam and I loved it, but there is something about the Pinnacle Class ships (Koningsdam, Nieuw Statendam and Rotterdam) that I love. They have a Grand Dutch Cafe which gives you another food option for breakfast, lunch or just a quick snack, not to mention a great cappuccino. I really enjoyed their music walk venues, BBKings, Rolling Rock Room for some great rock n roll and the dueling piano's were awesome as well IMHO of course.
Also Sunday, July 31st at 9 pm EST, on the Smithsonian Channel, the Nieuw Statendam will be showcased on the Mighty Ship segment. This will give you a great overview of the ship and all it has to offer.
Bottom line, don't sweat the small stuff, go and have a great time............