We fly Southwest whenever we can because we're a family of five and the Greyhound of the skies makes economic sense. Anyway, Southwest flies out to Denver more-or-less non-stop, and I'm a Rocky-Mountain-high kind of guy, and not just because of the subsidized family vacation known as the Aspen Ideas Festival (actually, it's not much of a vacation for me -- or, to put it another way, it's a vacation, but with half the State Department and a good portion of the Middle East diplomatic corps).
I used to like Southwest very much; it was honest in its cheapness, and its flight attendants were actually quite charming. But now they seem to have become very surly. On our flight back from Denver the other day, they were mean, short-tempered and dismissive. I know it's a hard job, but they don't make it easier by alienating their customers.
And there's one other problem with Southwest, apparently: They fly planes that have holes in their roofs (h/t Cindy Klein).