Yeah, I've never flown Southwest before. I despise the "cattle car" concept. I paid extra for their Business Select fare so I am guaranteed to be in the first boarding group.
But Southwest was the only carrier I could find that had a nonstop flight back to Houston late enough that I don't have to stay another night.
It's a 3-hour flight and 2-hour time change. My flight lands at 1:20 AM local. I probably won't be home until 2:00 AM.
Speaking of which: to arrive home at 11:30 you'd have to depart LAS around 6:30. I understand it's about an hour from Spring Mountain to LAS, so you're only giving yourself 90 minutes to return your car and go through security. Seems a little tight to me.