Key West: Suggestions for Xmas Eve & Xmas night
Some places will be closed for some of that time so be sure to call ahead and the ones that are open will be busy so if they make reservations, make them.
I am not 100% postive on these but this is a good start -
Blue Heaven is closed for one or both of those days
Mangia Mangia - is open for both
El Meson de Pepe - is open for Christmas Day
Double Tree is doing a big buffet on or both of those days
Cafe Sole is open both days
Casa Marina is doing something one or both of those days
Hot Tin Roof is doing something Christmas Day
A&B is also open and doing something.