Make a diagram of your room and openings, equipment, seating position etc, and fax it to Auralex. They will give you some thoughts about what type of materials to put where.
I understand your concern about many of the room tuning outfits that wseem to think it's on the same scale as rocket science, and should cost as much.
I got a lot of good information from auralex and used it to very positive effect. What have you got to lose for the price?