7.1 Help!

I've got some RT800's, RT1000P's, and a CS400, along with a Velodyne CT120. I know it's an odd mix, but I originally purchased RT55's as surrounds to go with my 800's. When I returned the 55's, someone else had returned the 1000P's which I couldn't pass up (good deal). I've been using the 800's as the fronts, 1000's as the rears with the post straps removed nuliffying the powered subs (worked best in my situation). I'm now, once again, interested in building an awesome system and need some input. I love my old Polks, but I'm looking to possibly move to a 7.1 system with the addition of an Onkyo 805 reciever and better sub. If so, should I find some used FX500's for the sides (using the 1000's for the rear with subs hooked up), or bi-amp the front 800's, which the Onkyo can do. I like music and movies equally well. Neighbors are not a problem in my situation, lucky me, only the 2 young ones get in the way. Basically I'm wondering if 7.1 is all that it's cracked up to be, or should I go with an amazing sound for music.