I tend to keep mine anywhere between 78-82 depending on the time of the year. Stability is the most important thing, you don't want to have large shifts during short periods of time (such as within the same day). If you choose to keep your tank at 82 during the summer I would set the heater at 80.5 or so in order to keep it from dropping too much if you keep your house cooler at night (or whenever). If you want to decrease the temperature during the winter, try to lower the heater by .5 degrees, wait a few days, then repeat the process until you get to the lower temperature you are trying to achieve, this is less stressful on the inhabitants as it gives them time to adapt.

Keep in mind you may need to use a fan or chiller to keep the tank from overheating depending on the ambient temperature of the room it is in, and your lighting and pumps will add heat as well.