[Anthony]

For 5.1, I would put dipole surrounds on the side walls, just behind the couch. If you are stuck (or prefer) monopole speakers, on the back wall will be fine, but just know that you'll have to dial in the delays (distance on some receivers) and play them louder to make the soundfield seamless.

For 7.1, you can do both the dipoles and monopoles and get a really nice soundfield.

good luck