I would suggest you treat the problem systematically where the room, speakers and electronic gear are a system that must at a minimum meet a set of threshold requirements that you establish. It also must operate within constraints. In your case the physical dimensions of the room, your wife's aesthetic sensibilities and cost. Any solution that doesn't meet the threshold requirements within those constraints should be removed from consideration. Also define a set of "goodness" criteria that are important to you but are not hard requirements. Weight those criteria based on their relative importance to you. Evaluate your candidates based on the overall score against these criteria. You've got a start but your requirements and criteria need better definition. For example, your statement about reference levels for music is unclear since there is no standard for it like there is for movies. What you need to do is establish a spl at the listening position that is a threshold requirement. If you are talking about concert concert blu-rays/dvds at 0 level on your receiver be cognizant of the fact that there is a wide variation between them in the amount of infomation that is sent to the center channel. This can put a real strain on the center channel speaker. I found this out the hard way.
With that said, here are some things to consider:
Your WAF constraint complicates things. I can't tell from the picture weather the right hand wall will be a problem but the left hand most definitely is. Without acoustic treatment it is going to be a real detriment in the time domain (first reflection) and the bass region. This will screw up spatial cues and if the speaker has poor off axis peformance it will negatively affect the perceived frequency response at the listening position. If acoustic treatment is possible that would expand your options. If something like this could pass the WAF gate http://www.gikacoustics.com/gik_artpanel_acoustic_panels.html
you should consider it.
If acoustic treatment is not possible then you should probably limit your search to speakers that have a smooth off-axis response.
You may want to look at speakers that are designed to be placed close to a wall to help with flattening the response in the bass region not covered by the sub. An Audyssey equipped receiver can help smooth out the bass some but is not a panacea.
Remember to add around 3db to the acoustic attenuation formula (20log10(r2/r1)) to account for the fact that the speakers are in a room, not free space when you are evaluating a speaker's ability to meet the threshold spl requirement at the LP.