Justin, if you haven't studied it already, note that the info on speaker wire found
here is essential reading. This is an area of audio plagued with charlatans selling magic wire at absurd prices. There's essentially no meaningful technical complexity involved here, and if your runs aren't unusually long you have nothing to gain by changing your present setup.
As to the surrounds, the side surrounds in a 5.1 setup can benefit by being located slightly(maybe 2')farther back than directly to the side of the listening position, to lend a little more phantom back surround in the absence of actual 7.1 back surround speakers. With 7.1 they can be directly to the side, with the back surrounds spread about as widely as the distance that they're behind the listening position. The surrounds can be placed about 2-3' above ear level.
