I'm a little late to be commenting on this topic, but just in case anyone wonders for next year...
Uncle John's Pancake House (Secor near Westgate) is open on Christmas Day. It has become somewhat of a family tradition for us to head there for breakfast after opening gifts.
This year, they even had someone walking around with a tray of complimentary egg nog (the non-alcoholic variety, of course).
Most of the staff we encounter there seem to be genuinely happy to be there - perhaps because the place is packed, customers are in a good mood, and hopefully most of them leave an extra-generous tip for Christmas. (That's what we do, at least.)