Too many choices, too little time!
I know it sounds weird, but I have a couple games, Skyrim and GT5, that I'm dying to play but know I need large chunks of time to really enjoy them, so I don't play and stick to f'ing around in Just Cause 2 or hoping online with one of the four shooters I like.
This really points to the fact that there are many fun games worthy of our hours right now, it's a great time to be a gamer!