Today I heard the most amazing Song at a local Music store. It was Gary Burton "Live" and the clarity of the instrumentation was astounding to me. I don't know the name of the song but his vibes were high in the mix. I mean that I wanted to look up at the sound of the instrument. The bass was placed slightly left center. The kick and snare were right center. The keys right bottom center and guitar was left bottom center. Everything had it's spot in the sound field. WOW. I suppose I had my 1st experience with 3D instruments were coming from everywhere  

This is an interesting article on LCR mixing which suggests that stereo placement is not as accurate as you would think: http://www.moultonlabs.co..._the_phantom_image/P1/

You can experiment with this by feeding a mono signal into the 'Channel Tools' VST and adding a small delay (.5 - .9 ms) delay to either the left or the right channel (The opposing set to zero of course).  The effect is very pronounced with headphones on.  I start with the pan at center, adjust the delay on one side, then make pan adjustments (if needed).
 
Seems to be most noticeable with sounds having a sharp attack, and reverb seems to really complicate things.
 
Glen

Thanks so much for your input guys! I'm working on using the info on a project this weekend