I hear is an amazing ship. I reccomend skipping Tortola and going to Virgin Gorda from there. First time St. Thomas I would reccomend the on island beaches and shopping, and excursions. However People that feel more comfortable in USVI I would say go to St.John.
I know is weird to read someone suggesting other islands than the Cruise Ship ports in. I can tell you that the most beautiful places in the Carribean are a ferry/boat ride away