How far apart do you position your speakers ?

I started with finding the best seating position in my room. I did this by ear, listening for the best balance for a smooth and articulate bass response. Then I placed my speakers front to back for staging/depth while maintaining good bass balance , then distance from the sidewalls, listening to female vocals in mono for solidity and focus of the central image, and finally toe-in for a final check on tonal balance and detail. They ended up about 85% apart relative to my ear-to-tweeter distance and toed in to meat at a point about 4-5 feet behind my ears.

When this was complete, I then checked speaker height/rake angle and toe-in angle with a laser pointer aimed at marks on the back wall. Finally, I checked the distances from the tweeters to side walls and tweeters to a center point on the back with the laser measuring device. Everything is to the nearest 1/16th of an inch. Sounds pretty anal, but this last step with the laser pointer snapped imaging and focus in place and the speakers disappeared to a much better extent than before.

This procedure is basically described in Jim Smith's book, "Get Better Sound." I had tried various test tracks, listening tones, etc, but always became frustrated with a lack of progress. I did the set up listening to real music and following Jim's advice. I found it worked best for me.

Depends on room and how far away you sit.

Doesn't the nearly infinite disparity between various speaker's responses in rooms, including tweeter off and on axis dispersion and woofer loading sort of obviate set-up formulae? And...has anybody CHANGED the speaker position months after thinking one has dialed it in due to some personal tonal preference change of heart? And is "formulae" really a word? As an aside...yesterday I draped a blanket (tastefully of course) over the back of the leather couch I listen from (providing some high freq. absorption on either side of my head), and it dramatically cleaned things up.

Hi Wolf, To answer the question:
"Doesn't the nearly infinite disparity between various speaker's responses in rooms, including tweeter off and on axis dispersion and woofer loading sort of obviate set-up formulae?"
I don't thinks so. At least as far as how your speaker loads or couples to your room. The idea is to be far enough from walls to avoid reflection and be close enough for proper bass reinforcement. Then to be in the right seating position to get the most from your soundstage.
I don't think that Whether you are 83%, 95% or triangle is any more important than understanding standing wave, reflections and reinforcement, this is where some type of formula could come into play. On or off axis listening is a factor of what your final frequency curve is in the room. As, I'm sure that you know, as you take your speakers off axis, you change the top end response heading down to your mid range. If your room caused some sort of peak, much of this could be alieviated when you go off axis, or if you have a very flat response, most of us would like to listen on axis.
Either way, the boundries, could be summed up mathmatically.

After reading all of the responses, I wanted to share my experience. I have a room that is 12 feet by 23 feet and i have the speakers on the short side of the room.The speakers come out 56 inches from the wall behind them and I have about 8 feet behind my listening chair. Because I only have 12 feet, I found that when I had the speakers spread to far apart, the sound suffered in terms of the most natural bass sound. I ended up settling for the speakers to be just over 6.5 feet apart with very little toe in. As I said, when i went any closer to the side walls, I did not like the sound of the bass. I sit 9.75 feet away from the speakers. This works well in my room. Every room is a bit different and you have to play around to get the best listening spot. Most rooms have issues but if you let your ears tell you what sounds right, you can usually get a good listening situation. You have to experiment and most of us have rooms that are less than perfect. Room treatments can help. Another factor is whether your spouse or you is comfortable having speakers come out in the room. As I stated mine come out 56 into the room, my dog Hanna does not object but not every spouse feels that way and there may have to be compromises.