I try to keep it at 68F in the winter (when I'm home and awake). I sometimes jack it up to 72 to take off the chill. I'm always cold due to severe anemia, and my body temp is normally 97.3F, instead of 98.6F. I'd love to have it higher, but can't afford to very often. At night, I turn it down to 60F-66F.
I usually use the fireplace at night, when I'm awake, as I'm usually alone with the cats in one room. They LOVE it. Jasmine usually "complains" to me to get it going, around 7:30 PM. A subtle hint! (Pacing back and forth in front the of the fireplace, doing her hoarse, "I have a need you must address NOW" meow.) Sometimes, I light it, just to shut her up!
A kerosene heater really works well. When the heater died last winter, it was a life-saver. We bought a 23,000 BTU one, and put it in the kitchen; I swear it even helped heat the upstairs, too. And the kitties loved it as well--when they heard me rattling the thingy to fire it up, they all would run into the kitchen, and cluster around the heater! The poor things must've been freezing. Downside: we have white cabinets and appliances--it puts out lot of soot.