This applies to every platform: consoles, PC, handhelds, everything. Do you have a couch, bed, special chair, etc?
I like having both my computer and Xbox on the same desk, and when I'm not on the computer chair I'm either on my bed or a beanbag chair.
Plus some members have brought up good points about display. Small screen or big? Lit up or dimmed rooms? LED, plasma, etc?
How bout you?