impact of room treatment

I am curious what benefits have been seen through basic room treatments. I was thinking of starting with panels in the front and back. I am looking for seperation of sound, the midrange. What component of the system would contribute most to this aspect?
I'm also giving this some thought but really want to find something that looks as good as it works. My setup is in my living room so I need my room treatments to look like ART. Suggestions?
dodge Im in the same boat. I have to consider looks and function as well as sound. Luckily I have a pretty understanding far.:)
I just ordered a swatch pack from ATS ACOUSTICS. They have several options of material to cover panels, traps, or whatever you go with. You can customize them with art or photos for extra $. They seem reasonably priced as well.
I have tile floors and the right side of my living room opens up toward the kitchen. Is the open area a plus or negative??

So it seems the first course of action is to treat the first reflection point?? How big should panels be?
I was using also Acoustic Revive products panels with very good results in my room for different set ups. Easy to place and very good looking wall treatment...they are stand or hang, so you can try them on any wall.
Ready Acoustics have very effective and good looking panels at a reasonable price and give free advice. My wife actually told me to buy some more of them; enough said! You will not believe the difference good room treatment will make.