I recall years ago a fairly empty plane from SYD to HNL and I announced to those around me before take off that once the seat belt sign goes off you can move to wherever you like and that the armrests fold up so you can have a middle row of 4 (I'm sure it was 4 and not 3). When we hit cruising altitude it was game on. Everyone ran to spread out. I had a row to myself and my travel companion had the row in front. Half way through the 10 hour flight I passed by 2 people in their original 2 seats near the window and said..bet your sorry you didn't listen to me.