If we go the route of a "Fat Section" on an airplane, I want a "Cryin' Baby" and "Typhoid Mary" section as well. I am fed up with people coughing and hacking on me on these flight (didn't these people learn to cover their mouths). I got a doozy of a cold a couple of months back after sitting next to one of these carriers.
In all fairness (and to stop being flamed), most of the babies that fly are well behaved and their parents know how to handle them. It is that instance where a kid cries the whole flight while Momma or Poppa have their headphones on watching the movie that gets me.
Earplugs can be a lifesaver on flights. I took the Screaming Baby Express back from Chicago in Janurary, sitting right next to a woman with her screaming boy on her lap.
The other thing to keep in mind is defensive use of the armrest. Getting it down and keeping it down helps keep the "person of size's" flab from leaning up against you too much during the flight.
I learned the hard way that this does not work on most turboprops, since they lack an armrest...