We have wood heat, so if the fire dies down overnight the rest of the house gets to about 63. That doesn't sound too chilly, but it feels cold to me.
Between raising our own laying hens and now dealing with an immune-compromised elderly parrot, I feel much better having a variety of heaters to choose from.
I've been using a 150w ceramic 'bulb' in a metal brooder lamp fitting over Mark's side of the cage. It gets pretty warm, so I have one thermometer on top of the cage and one hung at perch level inside. They are both wireless transmitting sensors that I can read from the receiver on my desk.
With just one corner of the cage wrapped in a towel, it was maintaining about 80-85, going down to 75 overnight.
I also have 250w infrared bulbs that I use to brood baby chicks, and just bought a 60w infrared bulb to set up with Mark's hospital cage. I also ordered a heated perch for Mark.
There are different wattages of the ceramic bulbs though, and I plan to add some lower ones to my arsenal. We used to have a large ceramic panel heater that mounted on the wall near their cage, but we never used it and took it down. Sometimes we'll put the hot-oil radiator type heater near the cage on low setting, but I don't like doing that for too long unattended.
Mostly we keep the fire banked enough to maintain the house around 70, but we're lucky enough to have an older house that someone took the time to insulate well. And my partner & I work different shifts, so there is usually only a few hours with no one home. We try not to travel during cold times of year, just in case.