Funny, I read your post getting the feeling that you would have to "settle for" the S/D if it's available.
I can tell you the Dolphin is one of our favorite hotels, period. Even in comparison with several of the "Disney owned" hotels. I'd choose the S/D over most of the Disney resorts.
During the holidays, The Dolphin lobby has a beautiful huge tree with a train going around it. It's quite festive. It has all the amenities of a deluxe hotel not to mention the awesome location and conveniences within the resort itself....Tubbi's which is opened 24 hrs. The grotto pool and the lap pool with the cafe right there. EPCOT & MGM are just a boat ride or walk away and you're right in the BC/YC/BW loop.
But, I can tell you...you may not be able to get a room there either for that time, they're also looking pretty booked up for that time. I'd call a.s.a.p....