Take out. I am too busy cooking for the holiday to actually cook supper! Subway, Chinese or Thai food, Olive Garden... as long as I don't have to make it and clean up after, it's a possibility for the night before!
I do "more" for Christmas Eve, but we don't usually do a big Christmas dinner, so I have the time/space/energy to prep a Christmas Eve meal. I try to do something to commemorate Seven Fishes, usually something like a seafood chowder or baked seafood casserole. Back when my dad was alive, there'd be 7 distinctly different fish dishes. I am not sure why... we aren't Italian or Catholic. I think he just liked seafood, had a couple of very close friends who were Italian, and it seemed festive!