I think a couple great points were hit earlier so forgive me for repeating them. I don't think its that difficult beings there are products to address almost every situation these days.
New TV on wall between the door w/ sidelights and window. Directly across from the fireplace.
Rotate the couches to the left and right of the new area.
Move the chairs to the rear in front of the fireplace. You can still see the fireplace and spin the chairs around to get warm.
The fireplace is a terrible place to mount a TV, IMO. Too high, heat and its distracting.
Blackout fabric and/or a combination of some HT blinds for the side windows. They will be your worst reflection offenders for glare.
Use the existing, previous TV nook as the new equipment shelf. Frame it out and use all that space to arrange new and future equipment.
The front stage for speakers is pretty easy and straightforward. Without actually seeing the room with my eyes, you'll have to be creative with speaker placement for the rear and back channels. Speaker brackets will be your new friend.
That's just off the top of my head. There are great suggestions in here from the crew so I would say its certainly possible. Best Buy couldn't design an audio system based around a toilet, let alone a real room. They did you a favor.
If all else fails, seek out a local professional installer from an audio shop. You can also check out
www.resmagonline.com for more information on custom installs and contact information.
Regards,
Mark
Polk Audio CS