my 2¢...
IMO, the dining room perspective should be considered as a priority in the overall layout of the A/V system.
(WAF should be considered within the context of proper system setup; not instead of it!)
Looking at the gaps and warts on the sides of the display (above the fireplace; ick!) and speakers etc... from the dining room will probably not be aesthetically pleasing, even to the *one who asked for it*, and might seem strangely positioned to guests seated at the dining table.
ie:
"hmm... why can't we see the TV from here?"
"hmm... the sound of that expensive A/V system is bass-heavy and muffled!"
Since you have a biggish budget ($15-$20k for speakers and amplifiers I assume), you might consider installing commercial-grade powered speakers that are designed to be built into a structure without sonic compromise.
ie: frame the study wall with sufficient depth to accommodate the equipment, speakers and (2)subwoofers; your lady will appreciate the understated appearance, and
you get World-class sound.
Genelec is an example of a top-quality brand of commercial powered speakers. They are compact,
very accurate, and can energize large spaces to THX reference levels cleanly.
You then only need the source components and A/V processor. (no external amplifiers are required)
The speaker amplifiers can be rack-mounted (for easier setup and better cooling) or integrated within the speaker cabinets.
I think I would place the 7th channel (surround back) near the dining area.
You can then set the system to "7 channel stereo" (your A/V processor should have an option to do this) for even coverage of the entire area, during parties or for background music.
The screen and center speaker could be mounted on a motorized elevator within the studio wall structure. (a drop-down hardwood cabinet containing the display and center channel speaker, from an overhead soffit/bulkhead, for example)
The main speakers and subs can be camouflaged behind fabric panels.
Broadband acoustic treatments can be integrated into the studio wall to kill early reflections.
ie: the wall framing is essentially finished with a layer of muslin hiding the OC705 panels, then covered with decorative fabric. (Acoustic treatments are definitely an important part of a "biggish A/V budget")
GL