The best position is different for every room because of acoustic differences and room size. However, they are very forgiving on placement. Normally, the rule of thumb is at least 2-3ft above your ear level when seated or higher. My bottom drivers on my Q's are 7ft off the floor and they sound great.
For a 7.1 setup, I like having my "side" Q's directly to the side of the listening area, for 5.1, just slightly behind. Currently, I have 2 rows of seating, so even though I have 7.1, I have the side surrounds just a bit behind a parrallel line of my ears when seating in the front row.
ps: can't believe you forgot you had Qs8's, lol
