Although the average traveler doesn't take type of variable into consideration I'm more likely to book using UA or WN based on this experience. I've been stuck in airports overnight (including 2 nights in DEN in Oct 1997 with a 10 month old and no hotel option) and it isn't fun. Why make someone risk this experience if they can delay the trip by one day on a space available basis? Bush league in my opinion but I don't make the rules.