Create an AirTran A+ account and see if your flights are available as award tickets for 8 credits one way. If so, you can create a Southwest account, transfer 19,200 UR points for each passenger to SW and then transfer those points to Airtran. 1200 SW points = 1 AirTran credit. Not sure about UR-SW, but SW-Airtran transfer is instant. If you want the lowest cost, also see if the itinerary is available on SW.com and for how many points - if you book with SW points you will have no bag fees.