I fly long haul Y pretty often and had never really paid much attention to which plane I was on. That ended when I flew the 787. I am female, 5ft10 (but neither chunky nor willowy) and shared my row with a couple of medium sized guys. We couldn't all sit back at the same time. I ended up hunkered into the window twisted slightly so that middle-seat-guy could twist and place his left should over my right and his right under aisle-guy's left.

Crazy. I was so knotted up when I got off I determined I will never fly 787 Y again.

Don't do it unless you are of very slight build.