Need suggestions on Speaker/AVR Placement

It's been a while, but I have a new project to undertake. Currently starting from scratch in a house with no prewired HT connections. Room is roughly 27'Lx24'W with a ~14' vaulted ceiling with large beam running the length of the room. There is a closet at the back of the room behind the couches which has electrical to it which I could use as a media cabinet. I have a couple of questions:

1) Due to the long HDMI/speaker cable runs to the front of the room from the media closet, would it be better to just relocated the AVR to the front of the room on a tv stand/console? The cable runs would be about 50ft long in order to run up to the overhead beam and then back down to the front/center speakers, TV(HDMI), and a subwoofer (RCA). The rear surround channels would be slightly shorter speaker wire runs due to them being closer to the media closet.

2) The room is currently stone/brick on the fireplace-side and loveseat-side of the room, with Mexican tile floor. Paired with the vaulted ceiling makes the room reverberate quite a bit. Will likely be putting down carpet, but is there any concern with speaker placement other than how I have shown below? Surrounds will likely be bipole/dipole with something like Paradigm Monitor 7 or 9's for the front 3. AVR will likely be something like a Pioneer SC-1222-K.

Any suggestions on layout? Would love to keep the AVR in the media closet with the internet router, etc, but if the long wire runs are going to compromise the audio significantly, I can move it up front. I appreciate any help as I'm pretty much a novice at HT theory.

Understood, and the furniture distance was just a rough placement and is open to movement. The TV will be a 55" plasma, wall-mounted, which by the 2.5-3Xs rule should make 13' about right from the couch. The front speakers, however, don't have much option for movement due to a doorway on one side and the large entrance to the office on the other. There is simply no more wall to spread them out, unless I went all the way to the corners of the room which would probably make the sound stage even worse.

I'd love to add something to absorb the sound reflection, but I'm not sure how much I'll really be able to add due to the loveseat-side of the room being two windows (6'Hx10'L each), long drapes will help some I suppose. The significant other won't be too keen on sound absorption panels in the living room.

I was hoping to be able to keep the AVR/possible HTPC/sat receiver all in the media cabinet, but if the runs are too long, I understand the complication.

Well, even at 13' from the center of the couch, it's only a small move forward from the current position, and doesn't pose much of an issue. It may help the sound imaging slightly since the distance between the fronts cannot be further than 7' apart. The theater room I helped build for my parents wasn't much wider (I think 10' or so) but it was a long room with stadium seating, so distance from their 100" screen wasn't much of an issue either, lol. The sound imaging in their 7.1 setup is great, but again, the room is much narrower than mine, and has drywall/carpet and no windows.

I guess the real answer I'm looking for (other than layout tweaks) is how much will it affect the power to the front 3 speakers having to run a 50' wire to them? I'm not too savvy on the loss of power, say from a 120-130watt per channel signal. I realize that power isn't driven constantly, but I always like the clean look of not having a half-dozen source units lit up in a tv console below the screen. I suppose I could put the AVR up front and run a few HDMI lines to the closet in the rear of the room in order to feed the signal from a BDP, HTPC, etc. Any thoughts on that option?

Well, I think I'll place the AVR up front, and run 3-50' HDMI cables from the rear cabinet for the Sat/Blu-Ray/HTPC. That way, the the AVR has short runs to the main speakers up front and to the TV itself. The RF-sat remotes or Harmony all-in-ones should be able to toggle between the AVR and Sat for most common functions I'd think. I can't think of any way to get the side surrounds lower than 7' high from the floor due to the construction of the walls (brick/stone), so hopefully a but of downward angle will focus the sound a bit lower to correct as much as possible. 14ga. cable will be used per your suggestion, Ethan, even though the runs will be shorter for the front-3. I suppose I could drop to 16ga, but I don't see much use in going smaller since I don't have any real limitations for wire size.