For TS: I have a 6m x 6m room and have tried both 7.1 and 5.1 with front wide/high speakers. The "Audyssey" effect of the 5.1 + wide seem to be provide the most perceivable surround effect for both 5.1 and 7.1 setups.
I agree also with the previous recommendations, have wirings for configurations already laid out while setting up your room. Really difficult to re-arrange cables once the ceiling, wiring channels, etc. are already made.