Peter, I hate to tell you, since you imply that your wife might comment merely about using the tape measure on the speakers, but that's just the half of it. Next, you'll have her take the tape and measure the distances of your ears from the floor and two nearest walls in order to determine your optimum listening position. Then, you'll do likewise for her. I'm confident that because of your dedication you'll remember and always use your proper position, but special precautions may be necessary for your wife. I'd suggest gluing a pair of footprints(bearing her name)to the floor in her spot. Putting her feet in the proper place will generally position her ears correctly, at least initially, but if you notice her slumping or leaning at any time, you'll have to remind her.
Now, some non-audiophiles might suggest that this procedure is rather low on the WAF scale, but surely a strong marriage can survive little things like this!
