I know you are already aware of the information found on PortReviews.com for each of these ports. Tom and I both wrote mega-reviews with detailed information about Aruba while on a cruise in December on the Brilliance of the Seas. You might want to refer to those sections of those new reviews found on the home page of CruiseReviews.
Also here is a link to a company that offers tours for all the ports you are interested in:
In St. Thomas, I just love to grab a taxi and head to Sapphire Beach for the day and return in time to do the requisite STT shopping.
In Aruba I would suggest you take a guided tour of the island (if you read our reviews you will understand why I make that suggestion) and spend the remainder of the day at Havana Beach Club. There are numerous guides available at the pier. Their rates are reasonable and they can be tailored to your needs.