I'll be on the Mariner from the 24-31, and yes they do quite a bit for the holidays. Theres a huge Christmas tree on the forward end of the promenade deck and lots of decorations throughout the ship. Plus on the first night and usually the 2nd night too they serve RCI's rendetion of Christmas dinner and it is very good. I actually like being on the ship for christmas, now that i've gotten older and our family doesnt try the Santa stuff anymore, its easier to be on the ship for christmas and let them take care of the festivities. I was on the same route during christmas last year and it was a lot of fun! I think you'll really enjoy it. If u wanna u can contact me VIA IM,PM or send me a friend request on my myspace: myspace.com/djcarolina. Looking forward to a great cruise, and if u have any questions u can hit me up with those too.