Speaker Width?

I have a similar room with similar dimensions. When my small maggies are in play they easily move to and from ideal listening locations to more traffic friendly considerations. When I have my big Green Mountain Audios in play (each weighs a hell of a lot) I have them on casters that allow me to role them into listening position and role them back to  accommodate foot traffic and aesthetic considerations. I use almost and equilateral triangle when considering and experimenting in appropriate placement and let my ears do the rest.  

Get rid of the girlfriend

Wait, does she have a sister that isn't so fussy? ;-)

A guy by the name of Jim Smith has been advocating a speaker placement width of ~80% of the distance to the listener.  Works for me.

There is more to it than that as others have mentioned.

https://www.youtube.com/watch?v=BOrZEreKB8Q

Mine are about six feet apart center to center, about two feet from rear wall, listening at about nine feet from speakers, cabinets tilted so that I cannot see either side of the cabinet at listening position. It works for me. Plus nobody else is here to not like how they are