This poll needs another option- I buy almost all of my games used, so opening them isn't an option to begin with. When I do shell out for a new game, it's usually something I'm really looking forward to, so it gets opened and played right away. I only have a few exceptions- a couple sealed games from the holidays when I (obviously) got more than one and picked others to play first (this includes Xenogears on the PS1), a copy of Zelda: Minish Cap I only bought to get rid of a Kmart gift card becuase we don't normally shop there, and the Miles Edgeworth game becuase I went on a game spree with my tax return last year and just haven't gotten to that one yet.
I don't sell my games, so I'm not terribly concerned about it one way or another- they'll all get opened and played eventually (not nessecarily by me, but someone I know will borrow it sooner or later.)