Herb Keller got Southwest Airlines going and was much celebrated as a CEO who knew how to get the mission and vision of the company "owned" by every employee- a feat that most CEO's can only dream of doing.
The current Southwest CEO and Chairman Gary Kelly favors serving larger airports that Southwest earlier avoided due to the congestion and delay in getting in and out. Over the years apart from being "no-frills" with peanuts and soda Southwest has really worked and achieved low cost. They are able to turn a plane around in 25 minutes by fine tuning their working with each airport they serve. This adds to another flight between two destinations compared to competitors every day. Think about turning inventory around quickly!
While some reports suggest that AirTran employees are also highly motivated - it would be interesting to see how much of the Southwest culture is quickly spread to the AirTran sections. There is little duplication of routes and a big advantage of the merger will be covering Atlanta which was not served by Southwest earlier to the Air Tran proposed deal. The merger needs to infuse the combined entity with "THE low cost airline" ethos that has made Southwest so succesful.