I had a chance to run the Room EQ Wizard software (free over at hometheatershack.com). This is the first time I have taken any 'official' readings, and it was really eye opening.

Unfortunately, I only have one place where I can put the sub in my room. Fortunately, just by turning the sub 90 degrees I got a huge improvement. I never would have thought to try this -- but the graphs don't lie. Check out the difference.