Our house is usually about 68 when we are home and 65 when we are not. Just those few degrees actually makes a difference . I was taught that to save money and heat efficiently, avoiding extremes was key.
We both grew up in old drafty homes with old furnaces. Along with some research on what makes sense to maintain a good temperature, these are the things I would suggest.
Don't turn the furnace off completely. By turning your furnace off, you make it work all the harder when you do turn it on. Just think of all the gas it is using when it has been off all night and you want to raise the temp in the house from 50 to 60. Even if you are going out of town for a week or two, don't turn it off. Up here, you run the risk of bursting pipes. Then you come home to a very cold, flooded house.
Windows should have curtains to block breeze and keep heat in. If the window are drafty, plastic sheeting works wonders. Even rolling a towel and placing that on the sill under the window will ease some draft.
Check the doors for wind. Adjust or add weatherstripping. A rolled up towel at the bottom of the door will keep the draft at bay.
Insulate your hot water if gas. This will help it retain its heat and use less gas to heat the water.
Programmable thermostats can help control the temperature and keep things constant. You can set home, away, and sleep temps.
Put on a sweater, dress in layers, or snuggle under a blanket with your favorite kids.
Also, do you have antiques in your home? Artwork that you care about? Books that are rare or that you care about? These things are not meant to be stored in very cold temps. They all need enough heat and moisture to keep them healthy. Most archives and special collections keep their valuable materials between 65 and 70.
Oh, and I'm with Mady. I have a hard time sleeping without that blanket weight.