We set both furnaces at 50 at night - with window in the bedroom open, Fantastic Vent running on low if the outdoor temp is above 50.. Only exception is when it drops below zero, then we set the furnaces at 65 to keep the tanks warm.
During the day we set the main furnace at 63, bedroom about 75 first thing in the AM and then off the rest of the time unless temps are below freezing.
As far as the stuffy AC goes. Set it to run the fan all the time and let the compressor cycle with the temp. You should do this in sticks and bricks as well. Keeps the air moving, the temps more even, and the compressor should run less.
We rarely use the AC at night, only in FL when it is hot AND humid. Then even with the AC fan running full time we find we need a small fan running in the bedroom to keep the air circulating comfortably.
Without the AC at night we keep the Fantastic Vent in the bedroom running all night with window at foot of bed open. We also have windows on both sides of the slide at the head of the bed so we can open those as well. Since those small windows only have one locked position at full open, we keep a set of 4 short dowels of varying length that we can use to prop the windows open just a little. Ceiling vent has a cover so rain is no issue.