As I have no insulation in the walls of my 1940's house it depends on the time of year. Right now it's set to 19c (66F), but as it gets colder outside I will increase that to 21-22 (70F-71.5F).
Whatever is comfortable. We have a small condo (perfect insulation on two sides - our neighbors). electric + gas is usually never more than $200, combined. We also just replaced our 1966 gas furnace with an HE one.
Right now we wait to make a fire when the house gets down to 62-64, but just let it burn out over night. Once we get into the real heating season we'll keep coals going over night and add wood in the AM and after work. The house stays between 62 and 70 then.
68F when we are home and awake. 65F when we are not home or overnight. Wife is not a big fan of those settings. My gas bill probably goes up $30-$40/mth per degree higher than those settings.