Hi 2family, and welcome to cruise-chat.
I see from the NCL site that your ports of call are Samana, St. Thomas, Tortola, and Great Stirrup Cay. What types of excursions interest you? For the most part, I've found the Eastern Caribbean to be pretty easy to do on one's own, so long as you've done some research, as Keith suggested above. Samana will be most difficult as it is a newer port. Great Stirrup Cay is easiest as it is NCL's private island and you don't really have to do a thing but enjoy the beach.
You can also check out our Caribbean Port Chat board, located here
for some ideas.