I open the windows. In the SF bay area, it gets down to 60 at night, very quickly after dark, no AC needed. During the day, I'm at work. During the evening, I'll sit outside with a beer and my dinner, maybe splash in the pool.
That works roughly anywhere, except you might have to open the windows more, as long as you can get a breeze going... and it's below, say, 80 outside. If there's a breeze, 60, 70, 80, whatever. If there's no breeze, it sucks to sleep at 80.