No RCI do not do 'all you can drink' packages; they offer a soda card for $6pppd or there is a wine package you can buy. Prices and selection are on their website.
They do not offer a drinks package as such, the nearest they get to it is a wine package or unlimited soft drinks like sodas both at a fee. You are able to check these out, there are different wines and in differing amounts, together with the soft drinks by going to their web-site. You should go to that site anyway so that you can fill in the required forms and find out about your cruise, all you need is your RCI Booking Reference Number which is peculiar to you. ... Neil.