Another suggestion would be to install a "soundproof" section in the back of the plane. They can run, jump, scream all they want and the people in the FRONT of the plane wouldn't have a clue as to what was happening. Of course, the parents would have to pay MORE, but ah, it'd be well worth it!!

I endured a 2 hours flight in front of a little &^%@# crumbsnatcher who kicked my seat the whole way. The parents did absolutely NOTHING!!