Airtran doesn't offer a lot of legroom, but their fares are reasonable from Dallas, and a connection will get you nearly anywhere. Customer Service is lacking; most employees seemed guarded and unfriendly (one forced me to use the computer check-in when I clearly wanted to ask the counter clerk a question first). On some of the newer places, free XM radio is offered (and free but uncomfortable earphones), which is a nice perk.
more