As a former UA Premier who flies out of DEN, I have to add a comment. I fly more and more F9 and always find ex UA flyers who are more than happy with the service. I will echo those comments above concerning personnel who are genuinely glad to do business with you the customer. I also notice that F9's pitch is such that when the person in front of you fully reclines, you don't get a nose full of hair! F( does seem roomier in comparison to UA. Best of all, no shuttle to SLC! In short, if your schedule permits, there is no reason to pay UA's premium out of DEN, let alone brag about it.