I think luxury is the wrong word. I have a hierarchy of US airlines in my head that guides my domestic airfare purchase decisions and Spirit is at the bottom. A

I think luxury is the wrong word. I have a hierarchy of US airlines in my head that guides my domestic airfare purchase decisions and Spirit is at the bottom. American and United are near the bottom too. I never fly first class or business class, so I'm always looking for the least miserable coach ticket. For me, that's Delta, JetBlue and Alaska. I imagine a lot of fliers think the same way and though their own rankings may vary, Spirit is at the top of nobody's list. And what's the difference is cost anyway? Maybe $40.