look at www.tubetrap.com for some suggestions. they've got a number of products designed for both constuction and treatment of sound rooms. tubegroover has some good points but you may have resale problems if you carry things too far (if that's a concern). i would go for 10 ft. ceilings and, at the very least, double wall (with airspace) constuction. some of the best spaces i've listened in were made of large mass walls, stone or double brick, etc. don't forget about controlling the sound of your hvac and NEVER install low-voltage halogon fixtures or lamps within 50 feet of your room.
New Dedicated Audio Room
I am in the initial stages of buying and building a new home. This home is going to have a dedicated audio room. (Approx 18'x 26') I will be working with the builders regarding the room and want to hear some suggestions regarding sonic improvements. I plan on using Hubbell outlets with 4 dedicated AC lines. I am also going to have the builders use thicker sheet rock for the walls and ceilings. Any other suggestions??