and just provide mga beanbags cguro (does it help in taming the room? absorption?) as for the drapes, my future missus will do that part, though i specified that they must be dark and thick. i am pretty excited on setting up the ht room, and i aint even watching my newly purchased dvds now, am saving them for the new set-up. thanks for the tips sir matz 
After you get the PJ experience, you would want to re watch all your DVDs again in the PJ. Dark is necessary but 2 curtains did the trick for me instead of one thick one, cheaper too.
You mentioned that you already put some acoustic treatment on the room so no need to worry on the absorption of the beanbags. Not everything needs to be absorbers in the room, others need to be diffusers too. Unless of course, your bean bags get in the path of the center speakers, whcih are usually placed low in a PJ HT setting.
My seating position is at 3.5 m away and the image is good (84x84 screen) , any nearer (referring to the bean bag location) and the image becomes less appealing and to some, dizzying. But in my experience kids love to sit nearer to the screen, so let them, they dont get dizzy easily as us OLD people.
If you got space behind your 3.5 m position for extra chairs then good for you.
Or if your sitting position is farther than 3.5 m then you can put your bean bags on the 3.5m location. This option would be better, you can slouch & put your feet on whoever is sitting on the bean bags
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If your screen is 70x70 however, no need to follow my advice, hehe, just put the beanbags anywhere.
