I just sit in my desk chair, elevating it to full height since my TV is on top of my dresser. I don't focus on a single game, instead I bounce around between a few. I actually just posted on a thread about the games I'm playing and for a super-brief version of that:
Castlevania: Symphony of the Night
Okami
Shadow of the Colossus
Final Fantasy IV & VII
Deus Ex: Human Revolution
Skyrim
Pokemon Red, Black, White, Leaf Green
Legend of Zelda: Ocarina of Time 3D
I'm a busy, busy gamer...my deviant-art watchers are going to stop watching since I keep promising them stuff and putting it off indefinitely but I think they get off on it (half of them anyway...)
Also, when I play 360 games, I have to use MY X-360. My GF has one but I feel more of a connection when I use my own rig and, controller.