I agree that your room doesn't really lend itself to a surround system- mine doesn't, either. I could, but since most of what I listen to wasn't mixed for surround and since it wouldn't sound great with surround, I haven't bothered. My system is stereo. Not 2.1 or 3.1, stereo. The dialog comes from dead center, right and left channel information come from the appropriate locations and anything between the two speakers pans evenly and without drops in level or detail. When I watch TV or movies, it works well and in systems that are less than very expensive/painstakingly set up and subject to glitches due to the technologies involved, I keep it simple.
That said, I think your system might be better if it were turned 90° to the left and the sofa placed so people can walk behind it, as they can with the chair. The walls to the sides of the speakers would be more symmetrical and the sound would benefit from that, IMO.