I'm over 3600 hours with WoW. I can safely say with Doom 1/2 I put in over 5000 hours as I played it every day for 7 years straight (avg 2 hours or so)
not too far off 300 hours with disgaea 3. Baldur's Gate 2, damn played through that a few times over the years, possibly over the 600-700 hour mark there (100% playthrough takes 200 hours in itself).
EDIT: how could I forget diablo 2. yeah I'd say I'm well over 300 hours with that too.