Another anecdote: I live in Belize and my girlfriend runs a hostel, and we can always tell which rooms have guests from the southern US because the AC will be set to 18C (~64F). For some reason northerners don't tend to do this, I assume because they don't use AC as often at home. The Texans I know are the worst. They make their apartments so cold I need a blanket if I'm going to stay for a movie, and they sleep under massive down comforters. In the tropics! It's so maddeningly wasteful. I rarely use my AC and sleep under a single top sheet with no discomfort.
I live where it tends to get hot and humid (not tropics humid though), but turn on A/C only if it's really unbearable at night. Even then, at most 5C difference. Usually, single top sheet, as you've said, a cool drink and maybe a fan is enough. I understand that humidity is tough though, but one can get dehumidifying alone from A/C or a standalone dehumidifier.
