Well, this question is a bit relative to the individual. With that said, you should still maintain a certain temperature in your house during the summer for greatest efficiency. Lets say you like to have your house at 76 degrees. One thing you should never do is leave the house at 85 all day until you get home and then come home and crank it up. If you do this you will be fighting against the heat load of all the items in your house, including the heat load your house has picked up through infiltration during the hottest parts of the day.
It is far better instead to reach the temperature you want in the morning and have slight system adjustments throughout the day as needed when the thermostat calls for it. If you have really poor insulation, like 1970-1989, then this will be tough. Additionally, leave your blower (AC fan) running for a couple hours continually to keep circulating the air in the home.
So to recap:
1) Most people like 76 on average. This is one degree more then the average of what our industry calls a summer day temp, which is 75. In winter that temp is 70. So set it at 75-76 and forget it.
2) Allow the air to circulate in the home by keeping the blower on for a couple hours. This will move the air through the dead warm spaces even after the AC has stopped.
3) Make sure you don’t have any wide open cracks, big or small, through which infiltration air can come inside, creating a negative pressure in the home.
4) Having the blower run means you will get more ACH (air changes per hour) in which to circulate fresh air conditioned air.
5) Summary: Set it at what you like, but typically 75-76