You can also look here:
You are right that a bad room can make a great system sound pretty poor. A great room will allow a system sound up to its potential.
There are a lot of general living situations that support better acoustics that typcially are better accepted by other family members for cosmetic/aesthetic purposes. Rugs/carpeting, soft furniture, drapes as well as items that diffuse sound waves (ie. book shelves, pottet plants, etc. . .). In my experience panels are left to address some pretty specific issues which can't be addressed effectively with proper use and placement of regular household items.
Other than the fact that a lot of the high priced marketed products are more thoughoughly tested (supposedly), I don't see any reason why custom building (DIY) can't really be just as good - particularly with panels.
The same can be said about some of the higher priced stands that are being marketed that consist of simple extruded aluminum and screwed together with the special connectors that can be purchased from the extruded aluminum suppliers. The price that is being charged for some of these stands is really a joke since they are simple to make and can look just as good.
Ckoffend's comments are excellent, I think. You can do an a lot in a room with ordinary furnishings thoughtfully placed. IMHO you should resort to acoustic materiels only when you have a very specific goal and a resolution specific to that goal.
BTW, there are a lot of questions in this forum about 'room tuning', they are, however often embodied in other thread's about problems with frequency response, i.e. too bright, no bass, etc.
Since you have a source for 703, look at the Ready Acoustics bags. Seriously consider double or triple thick.
Trying to figure out the best type and location of traps is not easy, even with a SPL meter and downloaded test tones or software. It often comes down to trial and error but the corners behind the speakers are usually the best start. In some cases, diffusion works better than absortion. If it's a bass problem, below 300Hz, some healthy skepticism of manufacturer claims might help prevent wasting funds. Below 100Hz, equalization like the Rives PARC can be the only practical choice.
703 absortion/ 125, 250, 500Hz:
2" on wall: 0.17, 0.86, 1.14
with 16" air gap: 0.66, 0.95, 1.06
4" on wall: 0.84, 1.24, 1.24
6" on wall: 1.19, 1.21, 1.13
Don't know error factor for above.
As far as I know, I'm the only one around here to build DIY membrane traps, which used compressed fiberglass along with hardboard in frames.
My room is so oddly shaped that I don't think I have any/few bass problems. I mainly want to treat the 1st reflection points and BETWEEN my Maggies. I think that will help imaging / staging.
My intent is to make 4"x2'x4' and hang them 2" from wall on 'standoffs'. There is a huge wall....12'x6' which is at a 45 and in a direct line with the nearest/left channel speaker.
WAF is going to be the decider. If I had a really deep pocket, I'd build a custom room of phi proportions and use some of the available sound control products.
I have the Radio Shack analogue SPL meter and the Rives disc which compensates for the meters response curve.
As a fellow maggie owner(20's) I've done quite a bit of room tuning.
Biggest improvment was as you suggest killing the side and rear reflections.
Adding traps to the front wall between the speakers killed the stage. Adding diffusion between the speakers opened the stage up.
A nice rug and the biggest leather couch you can get is also a good start.
I built a beautiful dedicated listening room in my last house. The final touch was home-made sound absorbers. It was an easy process; I made the frames out of 1x 4's and filled with O.C 702, wrapped them in cheap thin cloth. I had 2 2'x4' on each side wall slightly in front of each speaker. 2-2x4 on the ceiling a few feet in front of the speakers and 4- 2'x8' standing diagonal in each corners. I'd be happy to send you a pic if you want. They did make a difference and probably no different than the fancy stuff you pay hundreds for.