The last thing I'm trying to do is sound bad-ass here but... Did Dark Souls honestly take you guys over 100 hours to beat?? I don't consider myself to be all that great at it and my first play-through I finished in little over 30 hours, and that was exploring every nook and cranny. After knowing all the shortcuts etc. I can finish in about 8 hours now as well... although I suppose you guys could be adding up the times of multiple playthroughs and new game+ which might indeed justify that mark.
As for games that did last me 100+ hours...
-Dragon Quest VIII -Classic FF's -Star Ocean Till the End of TIme -It's a little fuzzy but I think Tales of Symphonia? -Binding of Isaac (massively underrated indie game by makers of Super Meat Boy) -Persona 3 & 4 (multiple times 100+ :D) -Monster Hunter
"Lighthouses are more useful than churches" - Benjamin Franklin
Any elder scrolls game, Both Fallouts (I suggest 3 over New Vegas), Dragon Age origins has 80 hours if you do everything then you can get the DLC. Kingdoms of Amalur, Dragon's Dogma and the Mass effect series if you combine all the games.