Due to air-traffic delay from FLL to ORD, missed DCA connection - the last one for the night. Decided to tough it out at ORD overnight. Interesting night. I counted about 10 others doing the same thing. I stayed at the AC until they kicked me out, then walked H and K, staying up as much as possible until exhaustion rendered me indifferent to the massive cleaning effort that takes place, not to mention the numeous PA announcements.