Here in northern Indiana we get really hot and HUMID days in the summer. My little house came with AC but I try to use it as seldom as possible. Luckily, the house has a full basement that stays pretty cool, and on hot days I turn on the furnace fan to circulate that nice cool air upstairs. I open all the windows overnight, and have window fans on the east side to push cool air inside all night. Then at sunrise I shut all the windows and close the curtains. Despite this, when the indoor temp gets to 82 (my melting point) I finally turn on the AC to about 78, but usually only have to do that a few days a year.
Now for a pet peeve. I have several neighbors who NEVER open their windows, but run their AC from spring till fall, night and day. Don't they realize how nice fresh air smells, and how lovely and cool it usually is? I just can't understand them!