Spirit Airlines is the airline we flew one-way into Texas (Baltimore->Dallas), in order to buy Shadowbeast (although we didn’t know what we’d be buying at the time). It wasn’t our first flight – we’ve previously flown on United, Delta and other smaller regional airlines, but it was our first flight with Spirit.
Spirit has an interesting philosophy about price. Ticket prices themselves are minimal, with additional fees for things like snacks, checked bags (which are limited in size, with a hefty fee for oversized bags, and strict limits on what can be considered carry-on), and so on (note that if you get more than a small amount of the add-ons, it will actually cost more than a normal airline’s ticket). The economy-class seats are reasonably comfortable, but there’s not much to do, so I recommend bringing a book or smartphone.
In conclusion, Spirit Airlines is a cheap, utilitarian airline, which I think is probably better (given that you’re only on the plane for a few hours) for us in particular.