Then on the weekend I logged on to AlierahP again, and went about my business questing and instancing. She's now 73, halfway through Dragonblight, and healed Utgarde Keep, Nexus, Azjol-Nerub and The Old Kingdom, getting some very nice quest rewards from them. It turns out I'm having a lot more fun healing with my priest than tanking with my DK*, so I'll probably be doing that for a while.
I've also been thinking about picking up and leveling another alt, although I'll probably wait on that a little. First, it seems silly to level all the way up from 1, when DKs get to start at 55. Not that I have any intention to level another DK. Second, and more important, I think I'll wait till I can get the heirloom items first for the bonus XP (plus, they have very nice stats). Then, it's open season on alts (at least on the realm I get the items in).
* Granted, that's because tanking heroics isn't working out so well right now, whereas healing is. Still, who cares 'why?' when the bottom line is that I'm having more fun?