How do I build the best room

Kevin: I built my room in the basement also. The biggest problem I am having is eliminating the upstair noise. Footsteps being the biggest problem. So far have disconnected the ceiling from the floor truss and put in ceiling joist. Not even the walls are touching the floor truss now.Used 4 inches of rigid mineral wool for insulation. In the process of laminating 2 layers of half inch mdf with green glue inbetween and half inch of quiet rock with green glue inbetween it and the mdf. I had a drop ceiling and will be putting that back in with 1 pound psf mass loaded vinyl on top of the tiles. The channels will be treated with silicone where necasary so they will be quiet. Perhaps your situation is different but for me the upatairs noise was more than I could handle. Plus to much of the music was getting upstairs in my opinion. I read a lot on soundproofing. There are 4 things: number 1 mass , 2 isolation, 3 damping, 4 absorption. My room is 14 by 20 by 8. Treatments are some absorption on long wall and 21 inch diamiter 1.5 thick inch pipe insulation for bass traps about 12 inches out from rear cornor.Big pipe insulation. The room is fantastic sonically hopefully it will be quite enough in a couple of months. Hope this helps and hope your room works well for you. Jeff

The room is a little on the smaller side for the 20.1, but we did (successfully) put a pair in a 13.5 x 18 x 7.75 room. The planars don't have a lot of energy dispersed towards the ceiling and they don't have a lot of bass, so they can actually work reasonably well in a smaller room. However, at this size the engineering is difficult. The smaller the room the more attention needs to be paid to room modes, diffusion, reverberation times. Small rooms are very unforgiving to design flaws--but it can be done.

Well, what a nice collection of responses for a first post! Thank you gentlemen.
I am not surprised at the comments of concern regarding placement of MG 20.1s in the proposed room. Does anyone have experience with a pair of hot rodded 3.6's with external X-over and multi channel amplification? Comments on the Magnepan Users Group forum lead one to believe success may lie therein.
The dimensions, excepting the floor to ceiling height, are somewhat flexible am considering at least two opposing non parallel walls- most likely the long walls. This may cause difficulty with long wall placement.
I will have a dip in the eiling to 7 feet one inch to box in the Header and plan on treating it with an absorbtant product as it appears to be at or very near to the first reflection point.
Thanks again gentlemen for your expertise in this matter.
Kevin