I really love the Death Knight start area. I think I've made/deleted at least half a dozen (that I'll admit too!) DK's as I love the progression changes.
My first DK, named Greaf is/was a gnome on my Alliance server. I leveled her to 65 as she had Inscription, and needed to ding 65 for the recipes. I never intended to level past that. DKs... too dang many of them, OP and why bother, right?
Well I did end up, just for fun playing with the guild on occasion with alts., and she was leveling very slowly. When I moved back to my Horde server I took Greaf, but her name was taken, so she became Biya.
A Blood Elf - yeah a Belf DK - none of those around - lol!!!
So, Biya came along to bring her Inscription skills (which she has maxed level and has ALL recipes including turning into a giant wolf - ftw!), again with no intention of max leveling her. She was quite comfortable at level 71.
My Horde GM, had a DK too, and we did start leveling together a bit. The addition of XP in BG's was a big motivator to continue as I do love PvP, but still with no idea what I planned to do with a DK if she reached 80. She is specced unholy, although people kept 'encouraging' me to go Blood or Frost, I've stuck with unholy.
Current spec is 17/54, but I've been looking on ElitistJerks and the new spec for 3.3 and may switch to that going out of Blood and into Frost. It looks interesting, although if I do, I'm going to find a way to put a point in Lichborne for that ability to give myself an oh shit heal with Death Coil.
So, Biya's been running instances and getting geared. She's in a mix of T8-T9 gear, and more heroic farming should get her better gear as wellas more learn to play time for me! I have thoroughly been enjoying her, more than I thought I would.
I've also been macroing her abilities/spells, working on a better rotation, which has improved my DPS too. That along with a few BG's has been keeping me busy.
Not too busy though as I've been leveling the Druid and the Pally - both fun to play too. More on those two later.
DK resources -
Death Knight Builds
Death Knight Info
Death Knight add-ons at Curse
Death Knight blog
Death Knight Tactics
Me and My Ghoul