Surrounds out to the side about as far as possible on the rear wall has good effect for 5.1. I have mine on the side walls with my seating area out about 18inches from the back wall and this works for me, I have pics in my link below.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70