For now I would have to agree with Gary. Play around and see what sounds best to you. Your figuration is what I would do too for now. I have went through so many rear configurations over the years. Still working on my present one. I live in a small apartment (12X12) living room with one wall open to the kitchen,so it's not easy to set up a 7 speaker system. I had a few different setup for my rears, but am going back to 7 speakers, I do think I got it figured out. Besides my rear couch is against the wall.
This is what I am working with now. There are still 2 of the same surrounds coming and 2 18" passive subs. Am I in trouble with my wife or what? Would like to mount the rears, but at 62# it's not an easy task, besides I don't want to ruin the beautiful paint job.