I try to keep the AC at 73 during the summer, but I usually have to turn in down even more at night. I cannot stand to be hot while trying to sleep, and the bedrooms are on the second floor so it is always hotter up there. I would use the ceiling fan, but my DH hates the breeze it creates. Last night I woke up at 4 am sweating, so I turned the fan on. My DH was bundled up under the quilt, and I was sweating! In the winter I keep the heat at 68-69 degrees.
I can't imagine setting the AC to 78 or 80 like some people -- I would be the grumpiest, sweatiest, whiniest person in the work at those temperatures!