I recently spent the night in the Denver Airport. I liked the little lounge area on level 6, it over looked the busy part of the airport but gave you a comfy feeling. Security was great, you could fall asleep and not worry about someone walking off with your luggage. It was one of the cleanest airports I've been in as well.
The best part was the bagel shop that was open all night... really good coffee!
I’m at that airport fairly often. Dallas, Denver, and O’Hare. One time I hit up Pittsburgh. The girl that sat next to me from Austin to OHare I saw later on the train thing in Pittsburgh. Weird how it seems some people follow you across multiple flights.
I'll be there again on November 5th.
I'm traveling North on October 24th and will be spending a couple hours in the Philadelphia airport. I had a choice between a layover there or in LaGuardia in New York City, that would have been 4 hours. I haven't been to either, but chose Philly because it's a shorter time.
I've found most main terminals to be cool so far. I'm looking forward to more travel over the next year.