Find a good stereo store and tell them what you're looking for. Take a reference CD and sit and listen to several songs.
FWIW, I have one particular track that'll tell me really quick how the frequency response is for any given system. It's Frank Sinatra, I Get A Kick Out Of You. I don't think every single recording has this, but on the particular recording I have, there's a nice fat bass trombone pedal tone right after the first line. ("I get no kick from champaaaagne," BAAAAAAAAAAA!) It's amazing the number of systems I've listened to that on where it's very muffled. So, that's the first test.
Then, I test the high response using drum & bugle corps music. A good example would be the 1999 Madison Scouts' Jesus Christ Superstar show. I'm looking for a particular timbre when the horn line is at full volume such as toward the end of Trial and Crucifixion.
Heck, I'll attach a test track with some snippets of the above for ya.
As far as speakers go, the Klipsch in-wall ones are nice. I don't think you should have to re-paper the wall if you do the installation right.
The speakers I've been most impressed by were Canton speakers - I don't know much more about them 'cuz I couldn't afford them myself back when I was installing them, but here's a couple of anecdotes for ya:
1) I was installing a new stereo/home theater/DSS setup for a guy at his vacation home. We got the speakers and such installed first, and while I was working on programming the remote, Channel 999 or whatever the "promo" channel that you get before you activate service is was on. They played a little musical interlude jingle that actually made me jump because I felt like I'd been teleported into a theater all of a sudden. Even more impressive is the fact that this happened before we installed the subwoofer!
2) My business partner picked up a pair of used Canton speakers for himself after our client's had impressed us so much, and of course we had to, uh, test them.
The sound was so clean that despite having music cranked really loud on these speakers only a couple of feet away, we were able to easily converse in normal tones. It was really weird, but really impressive!
http://www.cantonusa.com/