While I have no personal experience with ATI I would recommend them from what I have gleaned from reading reviews and these forums. Parasound and of course McIntosh are also a great choice. I think a A31 for the front three and a AT2004 would make a great 7.x. Of course you could go AT3003 and AT2004. Or even A21/AT3002 and Outlaw 7500. I prefer two amps vs a 7 channel. L and R are most important followed by center then surrounds and finally the rest. Unless you do multichannel music and have five identical speakers that would be an exception.
Edit: I believe the A21 is slightly better than the A31/A51 derivatives, but all very good.
Main Kef: Reference 205/2 & 202/2c, Surrounds: Kef XQ40, Velodyne Optimum 12, Integra DHC 80.3, Ayre K-5xeMP, Oppo BDP-103, Bryston 4Bsst2, Parasound Halo A31. Second B&W: 685 (3), CCM618, Def Tech Powerfield 1500, Onkyo TX-NR1008, Zone 2 Klipsch AW650.