I used to travel between the coasts bi monthly. If there were a small child on the flight it was always my great fortune to have the seat next to them. One can be a cross between Mother Teresa and Mr Rodgers at the start of the flight and be turned into a raving lunatic by the end of it.
Don't bring small children to the opera or plays or on airplanes unless absolutely necessary and IMHO visiting the grandparents ain't good enough reason