I asked my GIK rep about taking measurements and here was his reply "Only do acoustical measurements if you’re willing to do whatever it takes to make the measurements look good. It will mean a lot of big thick panels on walls and ceilings, and bigger ones still in corners. If you’re NOT going to do that, than your path is going to be deploying the best practical devices within the constraints of what will be visually acceptable. We don’t need plots to do that." I can tell you that my wife (and I really) would not accept that room looking like a room that is dedicated w/ panels scattered everywhere and most likely shut off to the rest of the home (if you are married anyway). Is this the fault of the speakers? IMO, yes and no as there are other speakers that are more friendly to more untreated rooms. One such speaker I have read about is the Ohm Walsh - which is also under consideration if I can't get the M3s to fully work - but hoping I can of course.
I have a thick shag rug, curtains along the front wall w/ 8' x 16' total of ABB1s incoming, 6' x 9' total of 242s incoming for the side walls (1st and 2nd), ASC planks on the back wall (both absorb and diffusion - and may add more later) and a big fabric OS chair just arrived from Pottery Barn yesterday. Once all together we'll see how that sounds and I may take some measurements but the only thing I would be add from there is bass traps - yes bass traps although since w/ the M3s there is little to no bass in the front corners - probably not.
Michael, that is my exact same issue - the bass sounds (and feels) the best along the back wall but that is too far away from the speakers and would block the "runway" to the MBR. I do think the sound stage is better with the chair where it is which is about 7' from the back wall.
Pics as the room sits now - waiting for the 242s and the ABB1s. As mentioned I'll likley add more ASC planks later as well. But that will about do it - maybe plants in the front corners instead of bass traps. Oh and of course the large box will be removed when it is picked up.
Speakers are about 4' from the front wall, 4' from the side walls, 7'4" apart and my chair is 10'6" from the speakers which is about 7' from the back wall. They look more toed in than they are because of the pano shot. They are pointed to just outside of my ear on each side. I've moved the speakers and the chair around a lot (but more fine tuning can be done of course) and this is where everything sounds the best except the bass along the back wall I'm missing where the chair is. There is some, but not as much.

