Something to bear in mind is that most people have their screens too high (mine is for sure). The screen should realistically be at eye level so you're not straining your neck when watching TV.
Old CRTs weren't hung on the wall, and that's not just because they were bulky, it made sense for them to be at eye level.

So, if you're planning on putting your plasma on the wall, think about where you're sitting in relation to it, and you'll probably find it needs to sit lower than you think