I bought down comforters for everyone in my family this year and I wish that I had done it years ago. For one, they have got to be the most comfortable comforter I have ever used. I feel like I'm sleeping in a 5-star hotel every night of the week!
But the other thing that I quicky realized was that down comforters are warm, really warm. For a long time, I've used an electric blanket on every bed in our house. I get cold easily and was completely addicted to my electric blanket. The problem is that electric blankets cost money to keep on. The other problem with electric blankets is that they really shouldn't be used on kids beds. There are some safey issues and kids have been known to overheat when using an electric blanket. There have also been studies done that seem to show some correlation between electric blankets and brain tumors in children. It's not really a risk that I want to take with my kids.
Anyway, down comforters are typically available in three different thicknesses - light, medium, and heavy. Heavy is at least the equivalent of an electric blanket and a few extra blankets too!
When buying a down comforter, consider fill power - which basically refers to the amount of down in the comforter. The more fill, the fluffier your comforter will be. Also look for comforters that have thread counts over 300 so your down doesn't escape. A down comforter that is baffled - meaning it has pockets sewn into the blanket to keep the down from bunching up - is preferable to one that is not.
Down comforters can be expensive, but if you check for sales you can get a really great deal. You'll stay as warm as you want to and won't need to pay for extra electricity or worry about safety anymore.
If you really want to splurge and have the money to do it, consider buying a goose down comforter. They are considered to to be the softest and most luxurious of all!