I may get some negative feedback for this, but I like hardwood floors with area rugs. The reason for this is to let the speakers sound bounce off the floor in the nearfield, but then get absorbed further into the room. I have done this in a few listening rooms with very good results. In my opinion in helps create a soundstage--now it won't work for all speakers, so I should qualify that I have done this successfully with Martin Logan speakers (which as most know are very finicky about placement, and have to have a reflective wall behind them to create a good soundstage to begin with). As for the carpet, a good thick wool oriental works great.
Listening Room Upgrade
I am having the carpeting replaced in my listening room and am looking for any ideas on how to improve the acoustic properties of the room while I am at it. The only ideas I have come up with are to put down 1/4" plywood flooring to stiffen the floor and to use non-synthetic carpet. Any help with material choices and installation methods is greatly appreciated. My current floor consists of modern floor trusses(18" O.C.) with 3/4" tongue and groove flooring. I do not think I can use a material greater than 1/4" for the sub-floor because of matching considerations with an adjoining room. God bless.