I read an article a while back about one airline deciding to weigh their customers and charge them at different rates. This would be a very beneficial policy to families with young children flying but I'm sure large people would not be thrilled. My last couple flights I have been sat next to large people. Frankly I'm sick of not getting to share the common area (arm rest) and having my neighbor spill over into my seat. I paid for 100% of my seat, not 80%. I would be thrilled if they had a couple rows that were designated for larger people that obviously cost more but perhaps not as much as first class because they would not have the extra amenities. You would have to buy these seats if you weighed over a certain amount and was traveling in a group smaller than one side of a row. I know this sounds rude, but I just don't get why I have to give a section of my fully paid seat to some stranger because they are fat and I am thin.