I keep my heat set at ~ 68 in the winter. I might try 66 next winter.
In the summer it can get hot and humid. I do have central ac, but set it at ~78 when I need it. When it's 90 outside, 78 seems nice indeed.
I try to use celing fans in the summer and plan to be better about dropping the shades over the south facing windows in the afternoon.
I do have a small screened in porch and I want to build a simple sleeping platform for it. Lots of times it's cooler outside than inside once my home has caught the heat of the day.