Historically I've found sleepinginairports.net useful for this kind of intel—I was pleased to discover just now that it's still around! Nearly 20 years ago now it saved me from a night of awful sleep. My backpacking buddy and I had just arrived in Liverpool with an early Ryanair flight out the following morning, and no hostel reservations. We'd been traveling successfully without reservations for a bit, but it turned out there was some kind of event that weekend in Liverpool and there was absolutely nowhere to stay (or at least, nothing that cost less than, like, the budget for our entire trip).

We decided we'd just stay out late, then go to the airport and wait it out for our flight. After some effort trying to sleep on hard plastic benches in the airport Burger King (where Michael Jackson's Thriller was playing loudly on repeat, I do not know why), I pulled out my 12" PowerBook and found out via that site that the airport had a meditation room with dim lighting, soft carpet, and no Michael Jackson. Ahh.

Random events are the worst. I was driving through Bend, OR and planned to grab a hotel room but everything was completely booked. Ended up just driving up a random forest road (public land, legal to camp) and sleeping in my tent. Was walking around with my headlamp in the night and some cops came by and asked what I was up to since people are often doing drugs there. Great. They came by and woke me up during the night again and I asked them to please keep record that I'm not up to anything so I could sleep.