Need Help - Difficult room accoustics

Thanks for your advice.

What do you think of a 5.1 ROCKET setup? This is more in my price range! :)

I'm not sure, but I think that omnipolars (like those new HORRIBLE Mirages!) are the LAST radiation pattern you'd want. You need to erase those cose sidewalls as much as possible. Tight-pattern HT speakers are best to erase the room as much as possible. Since the low bass may be VERY unpredictable in your setup, I'd certainly go with stand-mounted two-ways (so you could also adjust their height), and a good MOVEABLE sub). Any of a number of good monitors without a too-flaring tweeter (B&W is OUT!) should work well.
I'd try the Revel M20 ($$$), the Spendor S3/1p with its SC3 mate ($$), or any of a bunch of cheaper options. With the Revel and Spendor you can be assured of absolutely seamless front-trio staging as their driver-matching is without peer at their price-points. This will all help you erase the room.
Do make judicious use of thick carpeting, sidewall absorption (pillows propped on sofas, etc.), and possible dampening the farthermost sidewalls if you sense slap-echo.
Try to sit in the nearfield if at all possible. I recentl heard a 5.1 setup with the Mirages, and concurred with their dealer that they sound horribly swimmy. Yech.
Have fun.