The largest I cook for is about 40 - 50. I don't stand on formality; I always make a stew, chili, or heavy soup (this year it will be Cincinnati chili) and leave it on low heat with condiments (i.e., crackers, cheese, etc) near by. Guests serve themselves straight from the pot. I tried to do it all myself until I moved here and discovered that everyone will bring a dish no matter what. I also make my version of a trifle, since it is better made a day in advance. My husband like hummus, so I make that (also something that can be made in advance).