Though its open seating (after all the A-list flyers with numbers before yours have boarded) policy has caused many a family to  question the “family friendliness” of Southwest, especially for those flying Southwest Airlines with a baby or toddler, there is still one big reason Southwest Airlines deserves the praise of some family travelers: Southwest is one of the last U.S. airlines offering a significant discount for infants flying in their own seats. In some cases, a child fare may also be...