Getting to level 90 may seem like old hat this late in the expansion cycle, but I bet you all remember just when and where you first (or last) hit the level cap. For my part, after skipping out of WoW for all of Cataclysm, I decided to play all the way through each Cataclysm zone with my monk before moving on to Pandaria. The result? I hit level 90 pretty early in Valley of the Four Winds, before even getting around to doing any of Hemet Nessingwary's grind-tastic -- and experience-tastic -- quests. Though after that, I wound up jumping over the wall into the Vale in order to train flying because I'd not yet done the gate opening quests... so it's probably not a leveling experience I'll repeat.
Now that I've shared my level 90 story, how about yours? When and where did you hit level 90?