For what it's worth, I agree that an HT system brings even more challenges, since it's much more common to have multiple listening positions.
On the other hand you also have multiple speakers and even going from 2.0 to 3.0 makes a huge difference in the size of the sweet spot, taking it from maybe one foot wide to several feet wide.
I haven't tried treating an HT room yet -- that's something for next year -- but my guess is that (a) figuring out through experimentation what to do next is going to be even harder than it is for a stereo system, and (b) reaching "good enough" will be quicker and easier, so hopefully it will all balance out.
For the HT area I'm planning to hit the first reflection points, add some kind of bass trapping either at the sides or the roof peak, replace the Ikea bookshelf with a dedicated projector mount, and call it a day. Oh yeah, and maybe finally build a frame around my formica screen.
The room is basically the union of two square boxes cut in half by a solid reflective floor (probably what Mark's room looks like after a bottle of good whiskey) so I'm not aiming for "perfect".
The second picture needs one of those "Caution, HT equipment is not to scale" warning signs.
