If you want to know what to do in each port please go to this site that I direct every one to - go to google and type 'cruise ports call boards' - click on the the first result will give you all the info under the appropriate PORTS section on the page under each specific island. Once you sign up you can search within each specific category.
Wine by the glass can be purchased within the restaurants. I can also add that we take drinks into the restaurant that we have purchased from the bars prior to sitting for dinner. If you wish to purchase a full bottle then you may drink the contents over two or three days as the waiter will store the wine for you. Food on QM2 is excellent and now our favourite ship.
Hope this helps and have a nice voyage to the USA on the wonderful QM2 and a fantastic cruise in the beautiful caribbean. We have just returned having done the same and a smashing time was had by all. Cool weather but a smooth crossing on the North Atlantic but hot weather in the ports we visited - St Thomas, Dominica, Grenada, Bonnaire and Aruba.
You are kidding me - people can actually make a bottle of wine last 3 days - no way....!
I am going on a the QM2 for a return Transatlantic cruise, As a member of he Royal Navy do you think it would be ok for me to wear my Mess Dress, (Basically a black dinner suit with a short Jacket and miniture medals) or would I look a plonker or like member of the crew.