Unclejeff is correct. Good speakers come in traditional boxes with 3 channels per box -- hi-range tweetwer, midrange, and woofers. Expensive ones have huge handling power and big channels. Therefore, forget wall speakers.
Your case is similar to mine. I have a 42" plasma. Luckily, I have found Acoustic Research speakers -- Phantom 8.3 Series. The thickness is the same as the plasma, which can be hung on the wall next to the plasma. I'm being a devil advocate here about wall speakers b/c w/ Phatom 8.3 I'm getting more performance for less cost as no wall need to be cut an no wires need to be run inside the wall. AR had the 6 series and 5 series. For 8 series, handling power is 50-250watt, sensitivity is 89dB, 45-20kHz freqency response, can be either bi-amp or biwire. I was impressed w/ the spec. Last Dec, I bought 4 speakers of Series 8.3 and 1 Phantom 252C (Center) along w/ 4 beautiful aluminum-brush matching stands. I only used 2 stands. 6 months later, I bought 2 more Phantom 8.3 to do 7.1 HT setup. MSRP for these were $1250/pair and matching stands were $300/pair. However, these were discontinued at the time AR filed Chapter 11 last year. As a result, there are few left on the Internet for half price. AR still in business, and the Phantom Series still have 5 years warranty. You can use 8.3 as your main, and other series for surround. Those series w/ letter C at the end are for center speakers only. Just get powerful amp(s) and a separate pre-amp HT processor along w/ a HSU or SVS subwoofer for good punch. Cheap subwoofer will give "muddy" punch.
As the matter of fact, good flat speakers, which can be hung on the wall, are extremely expensive due to new technology. It's costly to be labeled as "early adaptor". However, they look beautiful, in my personal opinion.
Audiophiles won't like me for saying this, but I don't like Martin Logan b/c of the boom box at the bottom of most electromagnetic sheets. Can't hang them on the wall. For those that can be hung, they are not qualified as WAF (wife approving factor). If I had the lots of disposable income, I would buy ArtCoustic USA speakers. www.artcousticusa.com
Once I had found out about the ArtCousticUSA.com, I tossed out the idea of the traditional big box. I gotta think outside of the box. I haven't gotten a chance to stop by a local authorized dealer to do some audition, but I drooled when I was looking at the Photo Galleries on the website. Even though they have impressive spec, most Audiogon members would not considered them the best as those are not optimally built. However, for the price that I would have to pay for those speakers, they would better sound good b/c those MSRP are exorbitant. (Actually, they are supposed to be as highly efficient in power and energy as Martin Logan electromagnetic speakers.) The small one cost $1,100 each speaker; the mid size one cost $2800 each speaker; the big one costs $6400 each speaker. Custom cabinet color costs couple grands per speaker. On top of that, the art drawn on silk cost few grands more per speaker, depending on the size of the speaker. Ouch!
Currently, there are 200-watt Gekko speakers w/ MSRP $200 each, but 21st centy good.com is offering a pair for $145. However, you still have to spend money for the art like the ArtCoustticUSA. The art must be ordered from Gekko.com directly. However, for the total cost, I rather get the Phantom 8.3. Perhaps, you can use the Gekko as your surround. Again, they are supposed to be very efficient. Once you get flat speakers, you can get flat speakers wire to run them around the house on the wall. My flat wire speakers are from Acoustic Research, and they are biwire. I hid them behind the molding along the ceiling. For those on the wall, I cover them w/ good tapes and have them painted w/ a green architectual color to match w/ the rest of the wall.
(You & your wife will drool! I did.)