I moved to this new house a couple years ago, and just put my surround back speakers in storage because there wasn't a perfect place to put them. As is common, however, I finally got the itch to change/upgrade something, and since I already have the surround back speakers, I figured I'd try to figure out the best place to put them. I came up with the 3 location in the attached photo of my room, but each of them has a trade-off, and I'm not sure which would be best. Or feel free to suggest another location. I'm also open to the suggestion that less-than-ideal surround back would be worse than no surround back. I'm using a Denon 2113ci, so hopefully the Audyssey MultEQ XT will help forgive the less than ideal locations. So, here's my thoughts for the 3 locations I have in the photo.
1) This would put the surround backs about the same distance at the surrounds L/R, 5' from my listening position, and the same height, about 2' above my head in the listening position. The surround back right would be about in the right location, but the surround back left would be on the same wall and behind the surround left. I'd angle it to have all 4 speakers converging on my main listening position, but that surround back left would still be out of place. This is also the most intrusive into my dining area behind the couch, and my wife wouldn't like this since I'd have to move her wall decorations.
2) This position would probably be the most ideal if the back wall wasn't so far from the main viewing area. This would put the surround backs 10' from the listening position, double that of the surrounds. It would also be the most difficult to wire, and my wife would like this less than position 1.
3) This position would probably be the easiest to place, my wife would like it the most, and I could get both speakers the correct distance from my listening position. The downside here, obviously, is they would be mounted to the ceiling, about 2' higher than the surrounds. I'd angle them downward so all the sounds converged at the same location, about 2' above my head in the main listening position.