I do a massive Christmas party each year.
Tiny house, but 50+ guests. It's chaotic, but great fun.
Food: Buffet. Cold meats, cheeseboard, quiche, crisps, whole salmon, crudites and dip, Christmas Cake, gingerbread house, jacket pots,sausage rolls, mince pies, breadsticks, olives, antipasti, sweets, selection of puds - just any and everything. I always have a selection of frozen "party food" in the freezer in case we run low, but we always over cater, and end up eating leftovers til New Year!
I get in a selection of wines and beers, but people bring along a bottle too.
Father Christmas visits for the children. But mainly they entertain themselves, or rather the older children entertain them. Last year the girls set up a beauty salon in DDs room, and the boys had a big Nerf war outside (influenced by DD and DS's presents! I do expect parents to look out for their own children though - their responsibility to keep an eye on what they are up to.
I find that the older people and those with babies/v young toddlers tend to arrive first, eat and chat, and leave early. Most people with children stay til 8/9pm, but there'll be a hardcore group of drinkers til the early hours :)
It's hard work, but great fun