Hey,
I'm not sure if I will be of any help. But I just returned today from NYE cruise on the Magic. Our formal night was NYE. It was wonderful, our dinner was in Lumiere's. Then the second show, then most of our party went back to dress casual for the later part of the evening. But yes we were in formal long gowns and tuxes. Myself, DH, DS(18),DD(16),DD(8),DS(7) and my parents. I would say that 95% were dressed this way. The celebration was Disney at its best. I envy you next year, we aren't sailing again until 7/2009. Yes, there festivities for all ages until wee hours of the morning. Enjoy!!
Pam