i've never had a/c (though i do live in ontario where i can normally count the number of 90+F / high humidity days each year on all my fingers and toes).
i actually call it my "air conditioning", as in, "it's hot today, better get out the air conditioning."
the thing is it keeps you from sticking to the seat, and lets some air flow behind and underneath you. i find the sticky back is the worst part.
we'll see how it goes this summer - this will be my first year with a BLACK car. and these metros have a high glass area:interior volume ratio, so they heat up fast. (way faster than my old accord anyway)
I never use the AC, at all. The only time I use it when I give somebody a ride, they start complaining and I have to turn the AC on. If I didn't have the AC on the trip to vegas and drove 65mph I would of hit 40mpg for sure.
People that are fat or not trained get very hot and have to use the AC. I don't go to the point where I sweat or I'm extremly cold but I have ways of warming up quick and cooling off without cracking the window or using the AC. Pumping up tires at 1am in the morning made it easier for me against the cold. I changed my breathing techniques so I don't require a lot of oxygen. I know this because I can have my room's window closed for months and never get dizzy. The only time I open it is to get the new air in. I haven't run my AC for like a year unless somebody is in the car with me and they want oxygen.