In response to the comment "For the life of me I can't imagine why being on deck 7 is preferable to being on deck 6": There is no really obvious difference. However, people seem to be willing to pay to be higher up on all cruise lines, not just Disney. Moreover, there are 246 staterooms on deck 6, more than on any other deck. There are only 180 on deck 7 (and only 102 on deck 8). So, the corridors on deck 6 are the much more likely to be crowded or noisy. Maybe people are willing to pay just to avoid some of the crowds. Afterall, the difference in price between cat. 5 and cat. 6 is not that large as a percentage of what you are spending for the cruise in either of those categories.