Speaker distance

Six Feet apart center to center 
and 8 Feet listening position 

About 7.5' between the speakers and 11' from listener to speakers..

Another system is set up for about 6' apart and 8' distance.

Wilson Sophia 3's -- positioned according to the 'Golden Triangle'  - an equilateral triangle between speakers and listening position. Magic.

It seems to me that the ideal distance between the speakers varies from one recording to another depending on the mix and the instrumentation. I notice with solo piano and with string quartets that no one setup satisfies every recording. So I try to find a position that works most of the time. Maybe we need moving sidewalks with remote controls that would allow us to easily place the speakers close together for say, a solo guitar and far apart for an orchestra or big band.  

I agree. My listening chair is on wheels and I can easily move a little forwards/backwards (whilst seated) to achieve the best position. 

Dedicated room: use the 1/3 methodology, 1/3 length of room for distance of speaker to back wall; 1/3 length of room for distance of chair to wall. Then I used cardas calculations for distance from side walls. Fine tune toe in.
room tuning devices applied as well as bass traps in corners