We do an open house Christmas party each year. Never a clue as to how many people will be here. Isn't that a treat? Anyhow, I usually do a spiral sliced ham 10-12 lbs; baked ziti - usually a no-meat sauce in this as there's a possibility of a vegetarian and a vegan showing up; hot crab dip; turkey breast; tons of veggies/dips; sweet potatoes; bread/rolls; corn casserole; cookies; cakes; shrimp cocktail; chips/dips; garden salad; anything else that strikes my fancy along the way. The baking I usually do a week or so out. The veggie slicing and dicing no earlier than the day before, usually that morning. Ziti I can make up ahead and freeze if need be but I usually don't. Most of the cooking is just popping it in the oven so the only challenging part is coordinating temps and timing. I usually try to come up with a new dish of some sort each year so it's not too repetitious for any of us!