I am aware that there is another currently active Christmas-in-Paris discussion, but my parameters are sufficiently different that I don't want to hijack that thread.
I will be in Paris only for Christmas Eve -- landing at CDG at 17:30 and leaving at 10:00 on Christmas Day -- and will be meeting a friend for dinner. She will be staying in the 18e near the Marx Dormoy metro, but I really don't want to feel confined by where she or I happen to be staying. Rather, I'm looking for anything lively and fun, preferably on the more casual side (although I'll have a jacket and tie if need be), recognizing that the choices likely will be limited by the holiday. Cost isn't too much of an issue, especially for the right place, but don't want to go crazy either.