Besides WoW, longest game I have is about 115 hours on FF10, another 100 hours on FF12, and probably 70 hours or so on FF9. Personally enjoy the FF series a little too much sometimes
The Spyro games were pretty long for me. The one on the PS1 took me about a month to beat the first time. On my second try though I beat it in about 1 week and a half. All the Spyro games were good. And I spent a good amount of time on all of them.
I also spent much time on the GTA series. There all very fun to play. Just a free roam game were you can do whatever you please.
Fallout 3. Replayed it three times, 100+ hours each. Alot of games I have around 25 hours of playtime on, and GMod is on 600 hours until it got lame (that took a while!).