[AndrewJ]

The wife has recently wanted to turn on a small electric space heater on at night. I know that the thing probably pulls tons of watts, and it doesn't even heat the room up that much.

I recently convinced her to start microwaving 1L of water in a Nalgene bottle and keeping that under the covers. If you get the water just to the boiling point it'll keep hot nearly all night. Plus it's more noticeably warm than a space heater (or even an electric blanket)