If you fly with children, specifically minors under the age of 12, airlines should be required to seat families together without charging extra fees. There is currently an act in congress called the Families Fly Together Act which would bring this into law and require airlines to seat families with minors together at no additional charge. 

I frequently fly with my children ages, 1, 3 and 4 and if there aren't enough seats together when we book, we are often left to negotiate with passengers asking them to switch seats with us after we board. This is a frustrating process for everyone involved. I believe that airlines should carry the responsibility to group minors with their guardians without charging additional fees and making the Families Fly Together Act a law would make this a requirement for airlines.