As someone who has worked at the pier for RCI I can honestly say probably not! This ship usually sails full as do most of RCI ships do. You can try. The cabin guarantee is fairly new but they can't guarantee the best cabin. You really spend hardly any time in the cabin (or so I hope not), to me it's not worth the added expense of booking anything more than an ocean view. it's all in your preference though. The person who handles the upgrades would be the "Pier Coordinator" they will place a sign on the counter letting passengers know if upgrades are available. The purser's desk will not do this for you at all so do not waste your time in line. The ship sails with a few empty cabins for "just in case something happens" situations. Basically enjoy what you got!