You know, I played the older version of World of Warcraft, and it was an okay game. I was never overly impressed.
The only game I have ever been sucked into was The Sims 1 and 2. I tend to play the Sims 2 more when I am out of school...
EDIT: Now that I think about it, The Sims and WoW have a bit in common, they are both world simulation games (well.. moreover, the Sims is a single house simulation, but, still. Direct character control)
Control freaks!