I've flown Southwest to IAH before. The gate area there is a mess. No lining up because there's no room, they just call people 5 at a time, check the number and let you go down to the line gate where you officially get checked on to the plane. In fact, I was surprised Southwest flew to IAH in the first place, I thought they only flew to Hobby. Of course, I was also surprised to find JetBlue moved from Hobby to IAH.