Least Restrictive?

I'm home today only because I've been horribly sick. Yesterday was the worst, with fever & chills & such. But today I've started coughing, which isn't too great either.
Teddy hasn't gotten this bug yet (knock on wood) so he's doing pretty well. As far as this school year goes, he's spending a lot more time in self-contained classrooms. At first I was upset by that, but then I realized that he just does better that way, so I'm good with it. He only does specials (gym, art, music) & a small reading time in the regular ed 4th grade class.
I've got to say, the whole debate about least restrictive environment is puzzling to me. I'm not sure how I feel about the whole thing. Is this in the child's best interest? What if they just do better in a separate classroom setting? Not sure what I think about it all. I think a very complicating factor is whether you're talking about the child fitting into the environment, or the environment fitting into the child. In Teddy's case, trying to teach him in a class-within-a-class setting is very hard for him due to his attention issues. He ends up not understanding anything that is going on because he hears all of it at once!
Also, there's the matter of whether we're trying to make a child look like "everyone else". If Teddy isn't aware of & doesn't care if he's in a different classroom setting, does it really matter? I'm just so uncertain about the whole thing. And I know that no one else out there can tell me what is right for Ted--only he, & us as parents, can do that.