The most drafty spot was absolutely in the living room by the sliding glass door. Right now the plastic is like an over-inflated balloon... the plastic is taught from the pressure from the air seeping through the door frame. We put the plastic up and left the house for a cub scout meeting which lasted one hour. In that hour the living room temperature went up four degrees. AND it's not that cold out right now AND the wind is NOT coming from the South (it's really REALLY cold here during a South wind). But the room got a ton warmer just that fast. Which I hope means that my furnace isn't going to be running non-stop all winter. I'm very pleased and that's before I even see the financial benefits. I'm just happy the apartment is warmer.
For the record - I only have two windows - one in each of the bedrooms; and a sliding glass door in the living room. I had to buy a window kit made for sliding glass doors for the living room. And then I bought a kit for oversized windows... one kit was enough to do three windows, so I'll hang onto the extra for next winter. Total cost? $18.00