You don't have to buy a seat for children under two. They can travel as "lap babies" on most airlines. Certainly this is the most cost-effective way to travel. But it may not necessarily be the best. There are advantages to buying a seat for each twin. Most importantly, it is safer for children to fly in their own seat, strapped into an FAA-approved cat seat. If you do not buy a seat for each child, you are not guaranteed that there will be an available seat for them. Yes, there may be. But there are no guarantees. Financial strains mean that airlines fly fewer -- but fuller -- flights these days. Don't count on having a seat for your children unless you buy one.
Many airlines do offer discounted fares for children. This page provides some information for each airline's policy, but confirm the information with your airline before purchasing tickets.
Next: When should we travel?
