by Thanksgiving Airtran will be Southwest. The two are due to merge any time now. Southwest already owns Airtran and it is just a matter of time before they intertwine their schedules and drop a number of flights. No non-stops sounds like they already started.
They will not be combining operations until first quarter 2012. Considering prices I've been seeing posted, it would probably be cheaper to book AirTran and pay the baggage fees. In one case I saw posted, SW was $200 more. Are you really getting free bags?
http://www.southwest.com/html/about-southwest/lowfaresfarther.html
Southwest currently expects that the Federal Aviation Administration (FAA) will grant the airline a Single Operating Certificate (SOC) in the first quarter of 2012, at which time Southwest will work toward full integration. After SOC is achieved, Southwest will gradually transition the AirTran fleet into the Southwest paint scheme—one color, one brand. Ultimately, this acquisition will create an expanded low-cost, low-fare carrier with outstanding Customer Service and a unique Culture. Customers will be informed throughout the process with updates on southwest.com, airtran.com and lowfaresfarther.com. In the meantime, Employees from both airlines will continue doing what they’ve always done—delivering world-class Customer Service, operating efficiently and Safely, and taking care of our Customers.
They are already making changes in Dallas. The last Air Tran flight into or out of DFW is Monday Nov 21st. You can choose any other departure city on Air Tran's site and it gives you the rates. After Nov 22nd there are none for DFW. There are usually 16 Air Tran flights/day out of DFW and the same number coming in. There are now none after Nov 21st.

I need Nov 26th-Dec 4th.