Time will tell if it was the right thing to do or not.
Airtran has very little benefit with the business traveler,they are almost all leisure with not much incentives,ie FFM,allainces,etc and the list goes on and on.Delta is getting ready to take the fight to them.
U's international is better than what AW had which was almost nothing and PHL has great international presence/ potential.
The FL market is something that will probably never be extremely profitable no matter what because of all the competition. FL is a necessity for FFM and service destinations.
Without U's assets it would be a very steep uphill time constrained process that AW may have pulled off without U. Don't forget the votes on Wallstreet are very pro for the combination,that should say loads of the combination.
As to SW, to many hubs in the BWI area with DCA,Dulles(Metrojet),and PHL,something had to give. SW will have their own high cost problems soon as evidenced by managements concern with labor rates and fuel hedges running out.
AW has a fantastic mgt team that should bode well for the entire operation.