In a single playthrough? Jeez, well.. if you're easily distracted, you could get that kind of mileage out of The Elder Scrolls or Fallout, which are obvious answers, I would think. There's Borderlands and Red Dead Redemption, but 100+ hours is pushing it. Really shouldn't take you longer than 80 hours at most to get through your first playthrough of either game, even with distractions.
If you're really bad at the game, I guess Dark Souls could get up into that level of time sink, but I doubt you'd have the mental or physical constitution to tolerate over a hundred hours of Dark Souls without a new game+ to show for it.