Where to place room treatment?

As another resource, go to www.audioasylum.com and check out Jon Risch's DIY tube traps and absorbing panels. Very effective, innexpensive, and easy to make. I recently made 5 big (4' x 2.5') wall panels and 4 "Super Quick and Dirty" bass traps for about $250 Cdn.
Generally, you place the wall panels at the first reflection point and the tube traps in the corners of your room. And then you go from there.
Oh, I just remembered. The placement of your speakers is paramount prior to determining what room treatments (if any (?)) are required.

Hi,
Thanks for respond. How's about the front wall and the wall behind the listening chair?
Thanks!
Tran

Front and back wall treatments are usually best treated with a materiel that is diffusive as opposed to absorbtive, but much depends on the types of speakers you are using, their proximity to the walls, the location of your listening seat, and the source an amplitude of the reflections you are trying to treat. In my experience the wall behind the speakers is generally more critical and the wall behind the listener. FWIW, those room measurements you listed are mostly dependent on the location of your speakers and listening position - start moving both around and doing some remeasurements.

Good suggestions provided already, particularly regarding first reflection points which is the first area to tame.
You need to try all different potentials with room treatments, and without knowing your equipment, wall type, room size and materials, etc, it's not possible to recommend much. Many people like the live wall / dead wall set-up. You have to try everything depending on your room situation.
I have Martin Logans 4 feet from a hard wall surface, and the backwave was a killer. 2 2x2 auralex 2inch absorbing panels has been very effective in allowing me to turn up the volume much louder without the speakers glaring at me.
Bass traps are hugely effective depending on your room. I have 4 inches of the same absorbing panels all around the upper intersection of the room, and bass traps in the corners. Also have absorbing panels at first reflection point on the ceiling. I'll have to put up pictures some time soon. Is it effective - unbelievably - is it done yet - never.
I put everything up with the long push pins from Staples so I can move them around when I have nothing better to do, and to see what the effect is. Sometimes even moving a few inches makes a huge difference.

Realtraps.com has some good reading also. You'll be glad you treated your room. The bang per buck on the improved quality is very good. The sound quality is so much better you'll wonder what you were waiting for. I did.