The best seats for travelling with children are the bulkhead areas, near the bathroom, or by the window. Remember if you are sitting at a bulkhead row all your carry-on items need to be stowed in the overheads for take off and landing. During the flight you can place your items back on the floor. Don't forget you can order special meals for your children. Airlines do not charge extra for special meals.
Most airlines offer kid favourites, like hot dogs, hamburgers, pizza and chicken nuggets.
That way, no matter what happens they will have eaten and that cuts grouchiness. Flying is safer for infants and toddlers if you use a seat. Children who are over two years old are required to purchase a ticket and occupy a customer seat with a separate seat belt. Check with the airline regarding their requirements for children - don't take the travel agent's word. Get it in writing from the airline, that way there is no confusion.