I voted for 70, but actually I'd put it at 69. Not sure why you didn't just include temps 69, and 71, since that's the prime range, IMO.

Like others here, my wife would probably vote for about 75, but that's one of the concessions she made for me when we got married. It's pretty much the most important factor in my being comfortable, so it's really nice of her to do. We keep blankets by the couch downstairs

The battle I constantly face is that it's impossible to regulate the temperature in our small, two-story apartment. The bottom floor is this large, open floor plan room, and the top is two bedrooms and two baths. In the summer I shut off all the vents on the bottom floor and open all the ones on the top, and in the winter it's reversed. But it's still always hotter upstairs, and I can't seem to do anything about it. It's particularly bad in the winter, when I have to resort to cracking a window (which I hate, environmentally speaking). Any ideas? I think part of the problem is that in order to cut costs, there's only one set of ducts running through the ceiling of the bottom level/floor of the top level.