Drifter, although you've said that your speaker positioning is "perfect", you also referred to the "front" surrounds, so that raises a question. There are side surrounds, which in a 7.1 setup should be directly to the side of the listening position and maybe 2-3' above ear level. The back surrounds on the rear wall should be separated about the same distance as they are from the listening position and also be about 2-3' above ear level.
If they're already well-positioned, the next point would be that they're calibrated for a level that blends well with the front speakers(your auto-calibration on the receiver should do this nearly perfectly, better than you could judge by ear). Many sounds aren't meant to be "directional" and to be clearly heard as coming from the surround speakers. If your surrounds are correctly positioned and level-calibrated you should be hearing what the producers of the source material intended.
