Wanna Get Away fares (and all SWA tickets) also include up to two checked bags per person for no extra charge.
An optional charge is $10 per person each way to get Early Bird Check In service. That will automatically check you in for your flight and get your boarding number (SWA does not have assigned seats) 36 hours before your scheduled departure. If you choose not to pay for EBCI you will need to go online and check yourself in starting at 24 hours before your scheduled departure.
Other than that, and the assorted taxes and fees that all airlines have to pass along, there should be no additional charges.