Are you planning 5/7.1 for this room? Mono-poles are like a direct firing bookshelf. Multi-poles have drivers firing in different directions for a more diffuse sound.
http://www.psbspeakers.com/products/...e-S50-Surround
Gasman makes some good points about the layout. And by my guesstimation the side-surrounds would be located about where you might place the rear-side columns.
Aperion Audio, Ascend Acoustics, Athena Tech, Atlantic Tech, Axiom, B&W, Definitive Technology, Energy, HSU, Infinity, Jamo, JBL, KEF, Klipsch, Monitor Audio, NHT, Paradigm, Phase Technology, Pinnacle, Polk Audio, PSB, RBH, Rocket, SVS