It is so humid here during the summer that it's very rare that we ever open the windows. All of my windows are casement windows that have the bug screen on the inside. So the first change was to remove all of the screens and store them away until early Fall when we start to open the windows again. The reasoning behind this was all of the testing that's been done on solar air heaters using window screen as the absorber material. If it's that good of an absorber, I need to just get it out of the way and let the shade reflect as much light and heat back out as it can.
The second change was to make better use of my programmable thermostats. They have very specific schedules set to them now and in addition, the two guest rooms now have their dampers mostly closed on the days that no one is here using them.
The end result of this is some excellent news! At least my wallet thinks so. The total KWH usage for the months of June - Aug was down 4,255 kwh over last summer and the total bill for was down $365. So far for the year I'm about 9,000 kwh under the usage of my six year average.