I've just gotten my main to 90. And I have no intent of levelling another for a while. Which is a shame, as my old main, my priest, is still at 85. I'd like to play a warlock and a rogue at max level too. It's just gotten to that point where I don't like to level any more, and MoP levelling feels tedious to me.
I got rather irritated that as a tank, I only had four dungeons to level with, and past 86, two of those went green.