There is a way to do it if you are traveling w/ a group. I heard -- read RUMOR not fact --- that if your group books 40 cabins. everyone gets an up grade if there's space & they give you the option of doing an all inclusive for more money. Everyone in the group must opt in.
It's not a rumor-RCI does offer an all inclusive package for groups. You must have a minimum of 32 people and all members of the group must participate. It averages out to be about $50 a day. All drinks that normally sell for under ($5.50 or it might have been $6.50) are included. You have to pay for any higher priced drinks. There is limited info available on their web site at http://www.royalincentives.com/htm/FAQS_INDX.htm. Group sales has the additional details.