GO-NAD!, you are getting great input, and I will leave the most part of it alone. When the walls are down, run conduit, just in case you later realized you forgot to throw in some wire or other. Bigger is better of course, but I think I read the min would be something like 1.5" for a couple of HDMI cables, but with longer runs, even that might be too small.
IMO, going with a PJ is an absolute no brainer for this kind of room. THANK YOU for running it lengthwise (man, I've been frustrated by many others, including a particular friend of mine).
I would in fact think about what I'm thinking about. False wall, DIY Seymour fabric, three identical speakers. Now, your wife doesn't even have to see the following things in this room, all hidden:
-sub(s)
-treatments for front corner trapping (arguably best bang for buck spot)
-treatments for SBIR on front wall
-all three LCRs
This would be easy as pie for you, I am led to believe.
The Seymour fabric for say a 110" screen at 16:9 is about $100, and it's said with some frequency that this stuff is some of the best for visual/color accuracy. (However, in your case, I would buy more, so that you can "tilt" the fabric, so that the weave pattern is angled say at 20 deg; this only matters if you buy a 3LCD pj like and Epson or Panny.) It is also often described as the best for AT, as a weave, and not micro-perfed.
A PJ universal mount, pipe, etc, is maybe $200. You can save on pipe by going to home depot on having them cut something, and then you can paint it. Or you can do some hidden hush box, but I know that is an involved thing, and in fact depending on how big it is, might in fact be uglier. I do have a friend that had a cheap PJ, and he mounted some mirror thing right underneath it. I had no idea he even had a PJ (he was just firing at blank wall, which you will NOT do!). Or you can just shelf mount.
If you need a place to buy a PJ, I highly recommend AVS store. You can PM Jason Turk for quotes + shipping. There is an AHer who gets his PJs from them as well, sent all the way to Japan.
At 27'10" long, your proposed seating distance seems to be pretty close to 38%, or 10.58' from front wall. This is the accepted starting point for LP, for the best evening out of axial modes. With the inclusion of nonaxial modes, whether tangential or oblique, this figure may drop down to as low as 33% according to b pape.
Oh, if you do the false wall, that naturally means the screen is closer by a couple/few feet. The 38% still holds as if the false wall didn't exist, but the viewing angle has now changed. Let's say 8ft away, then I'd aim for about 75" screen if not slightly bigger. Now you might be thinking well that's not that* much larger than a 60" TV, but it's still like a 56% increase in size (see below), and most importantly of all, you can have the *truly* ideal setup for your front soundstage. Nothing beats three identical, vertically arrayed speakers all on the same plane.
http://tvcalculator.com/index.html?1678805c7b5675ec4932bfccb2a1d168
Feel free to ask me anything that you think I can help you with.
EDIT: I forgot to add, I concur with not only GG + double dry wall, but insulation too. I am well aware of the open passageway, but I still vote for this, if it's easy enough and affordable enough.