Almost any room will work. Some rooms work better without a lot of tuning, but anything can be fixed to sound better. There is no room that will sound ideal without any treatment.
What you need to do is find out what the problem areas are in your room and address those issues. A couple of resources you might consider are Robert Harley's book "A Complete Guide to High-end Audio." He deals with almost everything to do with this hobby. There is at least one chapter regarding the room. Another possibility is to check with Rives. They specialize in room alterations and construction. http://www.rivesaudio.com I have talked to them and found them to be helpful, although I know others haven't been as satisfied.
Realize going in to this that it will cost some money, but it costs less to fix a room than it does to buy better gear.
What you need to do is find out what the problem areas are in your room and address those issues. A couple of resources you might consider are Robert Harley's book "A Complete Guide to High-end Audio." He deals with almost everything to do with this hobby. There is at least one chapter regarding the room. Another possibility is to check with Rives. They specialize in room alterations and construction. http://www.rivesaudio.com I have talked to them and found them to be helpful, although I know others haven't been as satisfied.
Realize going in to this that it will cost some money, but it costs less to fix a room than it does to buy better gear.