Well, when I'm playing my N64 and SNES (u jelly?) I generally change between sitting up and lying down. Whenever I do ANYTHING I always have a large 1.5L bottle of water with me. Although, when I game I usually have a can of coke with me or a cup of tea at the ready.
With my consoles in the lounge room, I usually sit on the edge of the table, or move the footrest to the table and lie on it, using a cushion for a headrest. So that's a coupla feet from the TV, in a relaxed, lying down position. At the computer it's headset, leant back, hand on mouse and ready to roar!