Yeah, I hear ya. I have some definite "fluff" in my list of finished games, but the most challenging ones is where the satisfaction is at (at least for me).
I've been staring at Dark Souls, sitting neatly in its case for about a week now. Gotta tie off some loose ends (RE 4) before I dive into what will undoubtedly be a very long and punishing game.
Also, check out www.trueachievements.com
. Really helps put your "achievements" in perspective.