Yeah, I may have to pick up that game...
I'm buying Crysis this Friday, and earlier today, I was playing MOH Airborne. I really like that game, and even though people say its got a really short playability span, I don't tend to play games all the way through in one sitting. I've had MOH Airborne for quite a while, and still haven't seen the end credits. I just take my time, and take big breaks sometimes.
Same will be for COD 4. Its said to have a pretty small single player, but I know that it'd take me longer than most to complete anyhow.
Half Life 2, and its episodes are the only games I've completed in around the playtime people have said on forums, etc.