Austin.
San Antonio would be a worthy day trip too.
Both see (some) MD80s still, but don't book too far our (read: past the locked down equipment schedule) because the AUS and SAT routes that used to be all S80 all the time are seeing more and more 738, 321s, and 319s with every schedule change.
ETA: It's also very easy to get into (and out of) Austin on the cheap from the airport. Look at Route 100 (Airport Flyer) on the Capital Metro web site.