Consider have an energy audit done by a certified proffessional. This company is based in Washington and may be close. Green Energy Management, Inc.
A proffessional energy audit will include thermal evaluation of all doors, windows, floors, walls, and ceilings. Also, a blower door test that identifies were drafts are entering the house. And it will check for furnace air flow problems. Often these tests identify areas that need a simple fix to drastically reduce home energy consumption.
However, if you're only going to be in the house a couple years then you are correct in not wanting to spend a lot of money on long-term payback upgrades.