Pops - I have a terrible room, from an acoustics perspective. Past my left speaker, it opens out into two hallways (one continuing along the same plane as the front speakers, and one running at a 90 degree angle heading behind and away from the listening plane), and the remainder of the room also opens up off to the left. On the right side, I am closer to the wall, about three feet from the side, perhaps slightly less. The speakers themselves are about 11-12 feet apart, and they are about 18" from the rear wall (I might be able to get another couple of inches before WAF and fear of toddlers become the controlling factors).
In my room, with some rearrangement of furniture (but no dedicated sound treatments), and with the addition of a Velodyne DD-12 sub (which allows for a great deal of tweaking), I have my Thiels sounding "pretty darn good" to "very good." If you are wondering, yes, my room has huge bass issues, as in addition to those two hallways, my rear wall is really an archway, and I also have a very large sliding glass door along one wall. Plus, I have a very high, sloping ceiling. Without such issues, the 3.6's certainly do not require a subwoofer. However, in my dealer's room (which is not ideal, being an older building converted to use as an audio retailer, but is fairly well treated), the same or similar associated gear with my 3.6's is "extremely impressive" to "awesome." Obviously, I am using my own subjective scale, here, but the bottom line is that in a well adjusted room, with quality (and synergistic) associated equipment, Thiel speakers (especially the 3.6's, IMHO) will really show off what the rest of the gear can do, even when the associated equipment costs much more than the Thiels.
As always, though, your mileage may vary.
Tom.