My mom is very formal. At her house we eat in the sinning room, full place settings, good dishes, we have had to fight to do a buffet line to save some cleanup. She prefers passing the food. Very formal. We dress up. We do still all cook. My sister and I, my mom and our husbands, sometimes my dad if we are grilling steaks.
DH's family, no one has a house big enough for everyone to sit at a table. Do we just not get together? No, we have a blast. We generally set the eating time an hour before we really want to eat, so that we will eat within 30 minutes of that time. Someone is always late! This year it was the turkey. It is, by the way, cooked in a trash can every year. No, we are not red necks :). It is just the juciest, most flavorful turkey ever!!! We are very informal, but tuere are no parents or grandparents, just dh, his siblings, spouses and our 20 kids (current count....still growing!) We just have fun. So, we do both formal and informal...but we still all contribute to a predetermined menu.