The trouble is everyone congergrates in the kitchen! That's fine if it's nice and wide and has plenty of counter space, but awful if it's really tiny and the only means between the living room and the patio where your other friend is grilling.
I agree with other comments on how a dining room is kinda useless. If you have a big pot-luck, it feels more relaxed if people are just sitting in various rooms or outside with a paper plate on their lap .. and if it's just you and one other person, a couch works just fine.