Unscientific "Martha Stewart" approach - but it tends to work very well everywhere I've tried it...
Go to Ikea or somewhere that sells inexpensive 6' X 2' or 2.5' "runner" rugs. Something in colors and patterns that go with the style of the room. Thicker material is better in this case...
Stitch a pocket in one end that will allow for a 1" dowel rod (stained to match the wood) or use painted conduit, pipe, iron, whatever.
You can mount several of these at 7' high using those... You know, those things that hold pipes up - Like a shelf bracket, but with a dip in it (brain failure) to hold the pipe. Curtain rod hangers, you know?
You want these to sit around 4" from the walls. Staggered - Don't have them directly across the room from each other.
This way, you can kill some standing waves, absorb a lot of nasties, AND add an "artsy" touch to the room without spoiling the rustic atmosphere.
Heavy, dense furniture will help control low end a little... If so inclined, Auralex LENERD's in the corners may help a lot, and they're not too ugly, either...
A nice area rug on the floor may help considerably also...
Best 'o luck
John Scrip -
www.massivemastering.com