We're in Canada so we use Celsius but I'll convert for our farenheit friends:

23C/73.4F most of the time we try to keep the heat/AC off in spring/fall when it makes sense to do so.... We seem to generate a lot of heat inside (we have a lot of computers in the house) so it has to be quite a bit cooler outside to justify opening windows. something like 16C/60F, then between the heat from everything inside and the cold outside, we tend to keep rather comfortable.

My last place was an apartment and we didn't have control over the heating. Whenever it was on, we were cooking, so we left all the windows open all winter (the super knew about the situation and recommended we do this). The valves for the baseboard heaters were extremely old, didn't have knobs, and the super said he could try to adjust them, but there's a decent chance that they could snap and flood the apartment. Nobody wanted that, so we just left the windows open. For summer, I only turned on our AC at the apartment after the haters shut off. I wasn't going to pay to run AC to cool the place down while they were actively heating it up.... I'm glad we don't live there anymore because of that, though, everything else about the place was stellar. The landlord tried to get the owner to Green light the replacement of the valves while the system was not in use (namely in summer when they turned it off) since it would be easy to drain the system and do the work, but they didn't, so year after year, Windows open in winter. It kinda sucked, but we did what we had to. I installed a netatmo temperature system and at times in the dead of winter with all the windows open, the inside temps would read in excess of 30C/86F which wasn't fun. Hanging around in boxers with all the windows open in the dead of winter, and still sweating by doing nothing at all, wasn't great.

My new place has it's problems with airflow, but it's much better overall.