I basically agree with Dean.
But I'd go a little farther. With the room as configured, you're not going to get diddly-squat from going to 7.1 from 5.1. Seriously. With the couch on the back wall, there's no place for "rear" speakers. Just get the QS8's and do 5.1 and enjoy yourself. Mount them either on the back wall or on the side walls.
If you can manage the aesthetics of a vertical center channel, that would be cool (even a M2). If not, considering the listening distance, you might not get much improvement by going from VP100 to VP150.
That Pioneer seems like a really good value. Denons are very popular. I also like Onkyo refurbs at either accessories4less or shoponkyo.
You are a sketchup God.
I love the look of the room, and that should be a great system. Enjoy the journey, and keep us posted!
