Interesting thoughts, Frap. In a rectangular room I generally prefer to place the speakers along a short wall, and to sit well back away from them. To me, this sounds more like what I hear in a concert hall.
I think there's a reason for this - you see, in a concert hall, for everyone except perhaps those in the first few rows, the reverberant field dominates - that is, more sound power reaches the listener's ears via the reflections than direct from the instruments. Typically in a concert hall, the reverberant energy dominates by a huge margin - we still get our directional cues from the first-arrival sound, but the timbre is greatly enriched by the reverberant field (which also gives us the feeling of huge acoustic space). Indeed, the concert hall's feeling of velvety lushness is the product of a powerful, diffuse reverberant field. See Pisha & Bilello in the September 1987 issue of Audio magazine.
When we listen "near-field" (say a few feet from the speakers), the direct sound dominates. Proponents of nearfield listening claim that the recording itself already has all the reverberations you need, and any added by the listening room are distortions. The problem is, the ears expect for the reverberations to come from all around, not from the two points of origin of the direct sound. So while nearfield listening can give you holographic imaging (including depth), I get more of the "feel" of live music by sitting much farther back, where the reverberant field is dominant, and also where small head movements don't cause significant image shifts.
There is something of a tradeoff relationship between precise soundstaging and a rich sense of ambience - in concert halls as well as in listening rooms!
In my demo room, I have two listening positions - a single chair about 8 feet back, and then a couch about 18 feet back. The soundstaging is more holographic up front, the ambience richer in back. Probably a bit more than half of my customers prefer to listen from the chair, up close, while I usually prefer to listen from the couch - but (just to muddy the waters a bit) it does vary from recording to recording. C'est la vie.