Hi Steve,
I've spent Christmas in Turkey when I lived out there through the winter and being a Muslim country they don't celebrate Christmas. But many of the British-owned restaurants who remain open in the winter normally lay on a Christmas dinner.
They do decorate many of the bars/restaurants with decorations as they like to do that for their New Year celebrations. It depends on which resort you're thinking of going to, but most of them are closed in the winter due to the unsettled weather. Antalya is the best place to go to at that time if you want some sunshine - but even there it isn't always guaranteed. But it will definitely be warmer and drier than the west coast resorts.
It all depends on what you want. If it's sunshine, then Antalya is your best bet, but if you're looking for a Christmassy type holiday then Turkey doesn't really offer that.
Incidentaly, North Cyprus (the Turkish side) has the best weather of all at that time of year. Well worth looking into if it's sunshine you're after.
Strawberry