Cookies and sugared cereals make for sticky children. Small jars of baby food travel well. They have little waste and you can dispose of them easily. Unless you are certain you can clean utensils, opt for disposables. Airline meals may not appeal to all children.
Air travel tends to dehydrate people.
Drink plenty of water. Women who are nursing need to consume more fluids. Children often have trouble with pressure changes at takeoff and landing. If you call ahead, some restaurants may be able to prepare special kids meals. Encourage children to eat normally, but realize that a 'poor' diet won't hurt for a few days.