I have 2 forced air gas heating sytems. 1 is in the basement and has a contoller on the first floor and the other is in the attic with a controller in one of the bedrooms on the second floor. I have been told that there is a offset (+/- ?? degrees) in the settings between the 2 controllers (e.g.-upstairs 2 degress warmer than downstairs or vice versa) that will optimize the heating efficiency but I can't remember the rule. Anyone have a suggestion? Thanks for your time.

Never heard of that rule. The only rule is to keep the thermostats turned down as low as possible to keep from buring fuel while maintaining your personal comfort level.