Do you already have LCR speakers?
If not take a look at HTD.com..
They have the Versa line of speakers that are on wall mount thin speakers.
Look at the HTS1's, they will fill your needs for behind an AT screen really nicely. I have these in my livingroom setup with a sub and they sound really good.
Hope this get your creative ideas flowing..
Orotund Desert Theater:14'x20'x10',100amp service, JVC RS620, 120" AT screen, Carada Masquerade Masking, OPPO-203 & Panny ub820, Anthem AVM60, Simaudio Moon Titan 7&5 channel amplifiers, ACInfinity Fans, L&R Polk SDA SRStl Fully built, CC 2 Polk RTA15tl in Custom Cabinets Fully build, SS-BS Triad Gold, 4 Atmos 3 way Core5's, Subs-1 Rythmik FV25HP & 4 HSU VTF-MK5-HP, 2 Rows of 3 Seatcraft Excalibur Lx Seats and more.