That is surely a fine coupling!

Six feet is on the edge of overly close, though. Those speakers need a little bit of distance for the drivers to integrate, soundwise.

Listening height will be a big issue in such close quarters, as well.

Can't hurt to audition, though. Just set 'em up that way in the store.

I am clueless on LCD's and magnetic shielding. I don't know if it matters with those kinds of displays.

Let us know how the audition goes!

LCD (nor or Plasmas or DLPs for that matter) are not affected by magnetic fields so you should be fine on that front. Since the Vandersteens use first order crossovers I believe 6 feet may be too close (I'd call Vandersteen and get their thoughts on it though) for the drivers to integrate properly. Also because the speakers have sound coming out of the front AND back they like to be out from the wall behind them.

If I were you I would read http://www.vandersteen.com/pages/Techpage1.html and maybe even submit some of your own questions. If there is 20' to the side wall it might be better to rearrange the room so that the speakers are firing down the long way of the room (If this is domestically acceptable) this will almost always give you better sound. It may not only allow you to sit further from the speaker but also allow them to be further off of the walls.

I usually try to set speakers up using thirds or fifths (measure the room to the inch, divide by odd numbers under 10 and place on intersecting points.) But, since the Vandersteens use 1st order crossovers, you could set the speakers up against the long wall, halfway into the room, as long as your head is closer than 2 feet to the rear wall as described in the Audio Physic Virgo review from 1995:

http://www.stereophile.com/loudspeakerreviews/147/index.html

This setup works quite well. Images will still appear at the front of the room even though the speakers are close to you like big headphones. Of course, there is the issue of the speaker cables being halfway into the room, but, this placement gives you an option.

I currently have been using the model 3A for several years, but before that I had the model 2, and the placement is essentially the same. I have them about 3.5 feet from the rear wall, and about 6 feet apart, and about 6-7 feet from the side walls. My primary listening chair is about 7 feet back from the plane of the HF drivers. Did you say 20 feet to either side? You are saying that the room is about 45-50 feet wide then? If the distance from the rear wall to the wall the speakers face is less than 20 feet, the distance from the speakers to the rear wall may become hypercritical and room treatments may be necessary to solve resonance issues.

Over the years, I have found that the Vandersteens image best when the distance from the speaker plane to the listener is slightly greater than the center-to-center distance between the speakers.

LCD displays do not have the kind of high-intensity field associated with the electron-gun scanning of a convential picture tube; an LCD display can be placed as close as you want to the speakers.