I think what might be happening is you are trying to book more seats then AA has at the lower award. Sounds like they are willing to give 4 away. The 5th seat is asking for more miles.

I suggest booking the 4 you can get right now.

As for the rest of the seats that is your call. I personally would not do SWA. First, they don't fly to DFW they go to DAL. That means a cross-town cab. At the same time, SWA delays mean zero protection with AA if you are delayed.

I'd suggest keeping everything on AA and either pay a higher number of miles or try another gateway. Without dates we can't help you with other city options.