What is very good imaging and soundstage exactly.

I do not often listen to systems other than my own and so I don't have much to compare to. I'm really curious what others are hearing when their systems are dialed in, especially regarding the soundstage thing. Briefly, what I hear from my sweet spot goes something like this. Always a focused center image.....it often seems to be coming right out of the center of my preamp, which is 3 feet behind the plane of my speakers and centered. It will move slightly if I move my head from side to side. On most recordings, the soundstage is mainly back there as well, somewhat behind the speakers. Once in a while, a part of the music seems to come directly from a speaker.....like the banjo player on Alison Krause/Union Station.....that boy lives in my right speaker. It sort of bugs me that he is right at the speaker, rather than behind it, but this doesn't happen very often. Most of the time my speakers disappear quite well. Once in a great while, I hear information outside of the speakers to the right or left. So my question is, is this good or bad, is it normal? Do you have favorite recordings that are impressive in terms of soundstage, and what do you hear as far as depth and width, etc.?