Did a night at MAO (Manaus, Brazil), would definitely not recommend...
Airside is always overcrowded with departures 24 hours a day and barely a seat to be found, despite not being allowed to clear security until 3 hours before your flight. Landside seating is mostly limited to the food court, so not very comfortable for sleeping. The limited seats available all had the built-in armrests. Also with the need to be careful about your belongings, it's difficult to get a good night's rest. Luckily there were several of us so someone was always awake at some point during the night.