Our condo sports a loft style environment with a very large living room divided from the open kitchen by an island counter. At our parties, the back counter is where we locate the "buffet," a beverage station is on one side of the center island counter and the "sweets" are located on the other side. Everything is self serve and if there are any confusing parts, we post small signs explaining, for example the different flavor dips.
We have had as many as 40 people join us for a birthday or Christmas celebration. EVERYONE hangs out in the kitchen and around the counters. The other side of the OPEN living area is usually empty. Not a chair occupied, not a sofa sat on. The Den/TV Room is empty as well. People are happy crowding around the kitchen. We don't fight it ... we join it.
When I was growing up, the rooms of our house were more discrete, one wasn't open to the other. The kitchen was separate from the dining room which was separate from the living room which was separate from the den/TV room. Guess what ... usually the same thing happened. "EVERYONE to the kitchen/dining room ... get your love, warmth, nurturing, sustenance ... step right up ... crowd right in.