American Airlines and Southwest have round-trip flights from Austin and San Antonio (AUS, SAT) to Miami, Los Angeles, Nashville, or Phoenix (MIA, LAX, BNA, PHX) for $139-$171, NONSTOP. Flights August to November. Departures on Monday, Tuesday, Wednesday, Thursday, and Saturday. Extended weekends available. Origin/Destination reversible. No Thanksgiving dates.
Note: Southwest is matching on some of these routes but to get the discount requires jumping through a few annoying hoops. First, you can only see the fare in their slow and buggy Southwest (mobile phone) App. Second, you have to use code “BDAY”.
Phoenix is the most expensive fare in this list at $171. All other destinations are about $139-ish.