I think its a nice idea to have big banquet tables set out and the food laid on the tables so guests can just pass things along and help themselves.. It gives them the flexibility to pick and chose like a buffet, without the school canteen vibe. It offers sit down style like table service but without the formality..
It also promotes relaxed interaction as food gets passed around, people help themselves and everyone digs in..
This picture sort of summarises how I imagine it would go
image from Real Wedding Style Magazine