Two surprising things I found that improved my imaging and staging...

http://www.acoustic.ua/forms/calculator4.en.html

Here's a site where you populate in detail your room dimensions including ceiling height, the locations of you speakers, the height of the speaker drivers, your listening position, your seated ear height and the program will show you the 1st reflection points on all the walls, the ceiling and the floor of your room.  Good tool vs. the mirror method. 

Don't feel bad willy-t many have made the misteak of misunderestimating my intelagence. 

nobody ever underestimated his Eggo.

One of the biggest mistakes, IMHO, made with spkr placement is many people instinctually place them way too far apart.  Thinking it will present a large stage, image etc..  This will usually have the opposite effect and will damage the overall SQ. 

It "may" seem like its large, but once moved to proper center to center distance (as well as the other dimensions), things lock in and SQ is improved significantly many times.  The 1/3 rule and cardas calculation are good starting points / ballpark and reveals how far off people miss the space between, distance from side and rear walls. 

Understanding shared spaces present a lot of restrictions on placement, so it's always a compromise and there are no exact formulas for placement, just guidelines - but those guidelines (physics) usually provide pretty consistent results.

However, if you have the ability to at least try some of these "guidelines" its worth it, for no other reason than getting experience.  Even better, when the wife is gone, remove some of the furniture "in the way" temporarily, move the spkrs out into the room as well as play with the listening position, just to hear what your system can or should sound like.  Understanding your room acoustically is massively important.  It does take work though. 

It really comes down to how much effort one wants to put in getting the most out of your rig and good enough is totally fine if that's what suits you.