I was quite amazed to read above that the center of gravity range is 20 inches or something on an aircraft that's 1,500 inches long. And judging from the weights shown on wikipedia, a half full 739 must weigh 140,000 to 150,000 lbs. I trust the airline's calculations and all, but from a customer relations standpoint, it seems like they could move customers from rows 22 - 28 further back in the plane and accomplish a similar effect.