When people ask me why I chose to live in Charlotte I would often say “it’s a hub for a major airline and Southwest doesn’t fly there.” It sounds like the second part of that might no longer be true now that Southwest is buying AirTran. I like how AirTran has assigned seating. It can only be reserved in advance for a fee or you have to wait til check-in, but I know if I book a rear seat that I will board earlier and have room for my bag.
Other than that AirTran is pretty much crap to and mainly just serves the niche of cheap last minute tickets to BWI and ATL.
Southwest has wanted gates in CLT for a while so this gives them 2 unless they do something to trade for others.