Mine's the kitchen table, square, counter-height. This way I can stand and trade sometimes. (I think sitting in front of a computer for a career is very unhealthy). I can't use a spare bedroom for fear of annoying the neighbors with my screaming. Can't trade with any sunlight...all shades. And music kind of distracts me, but less so now that I've been trading for a few years and have my system down.
Temp is usually in the 70's.