That's the kind of question that comes to mind at first glance at an idea Airbus has asked a patent for...a circular seating arrangement, in tiers. OK, that's a little hard to grasp, so here's a drawing submitted with the patent application.
You'll notice that the seating arrangement would require a fairly radical change in the shape of the plan, toward a wider profile. Several of these circles would make up the plane.
So why even think of it? It turns out that this idea—which is so far only an idea, relieves a longstanding engineering problem of large planes. The rows and the air pressurization puts stress on both ends of the plane, forcing engineers to add heavy frames at both ends. Eliminate the problem, the plane becomes much lighter.
But where do the overhead bins go?