Spence, it be the answer in my view that since the vast majority of the material reproduced by the side and back surrounds is rather ambient in nature, a more dispersed rather than sharply focused presentation is advantageous. The surrounds therefore shouldn't be aimed directly at the listener.
As to their placement in the room, your arrangement sounds good, but to comment on a point John B. mentioned, with actual back surround speakers present, no help from the side surrounds in forming a rear sound field is needed. The sides don't need to be slightly farther back as is suggested for a 5.1 setup. They should be directly to the side if possible, or even slightly forward if it isn't. Of course very small variations in this aren't critical.
Thanks for the replies!
In checking last evening, both of my side surrounds are in fact slightly (10-15" or so) ahead of "my" listening area. I say "my" because the seating consists of sectional sofa with a 90 degree bend oriented in the shape of a left-leaning "L". My area is on the extreme right (with access to lighting controls and phone ...because if I sit down to watch a movie, my brother will almost always call me). The elbow of the sectional is about the same 10-15" rear of the sides, and the left end is about 24-30" ahead of the "surround" speakers mounted on the side walls. The sofa ranges between 9-12 feet from my modest 75" screen.
As previously stated "multi-use" (Home Theater/Family/Game etc.). With the sofa, carpeting & acoustically absorbent suspended ceiling panes, the room is reasonably "dead". Nothing that my soon-to-be-delivered Marantz SR7007's Audyssey XT32 can't correct! :-) Can't freakin' wait!
