Repetition in leveling gets really old fast going through much the same content. But I just tried to find other ways to enjoy the leveling aspect while doing so to make it fun. I made my DK somewhere back in early April 09 after I came back from my long hiatus from WoW just to get the experience and feel since during the time I was actually in WotLK Beta I never spent any time playing one since I was just focused on Paladin stuff back then in beta.
It was fun to get the feel of the class playing a DK but I was never fanboy as WoW goes about playing one. Looking cool is one thing, but play mechanic is still something you have to actually enjoy after you get beyond the look of a class. What did appeal to me was that DK were a melee class which I liked and more easily understood to various degree. As well they were just anti-paladin and since I played a Paladin for what seem forever it was just good to play something opposite or anti class wise how I always played as my Paladin.
So started my DK Alithas and just leveled him up slightly to lvl 65 just to play around with Inscription at the time mostly. So for months he quietly made errands in Ogrimmar just milling/inking and selling Glyphs as side income. He did well in peaceful coexistence with the market at the time. Market has since changed a bit.
So since one my goals preparing for WoW Cataclysm was to get my current Alts leveled up so in action I had to level up my DK. A old friend rolled a DK and was now playing on my server so that played a bit into that since we both was playing one. So I spec'd and level my DK as Unholy because I found it appealing and just to be anti-paladin and anti what I've always played. Spread disease and pestilence vs curing it. Sometimes I really just swimming against the tide of things.
Leveling my DK I actually had to relearn how to play one since my DK sat for months not played. Was fun to level but more so learning and skilling part and going through the paces vs just going through the content. So the learning and skilling part was fun. Leveling is still and was much a pain. Nothing new leveling but it seemed easier to level. Dealing with casters leveling was a way to get revenge as a DK vs back when leveling my Paladin when casters were always a pain. I still found leveling my Shaman more fun overall vs a DK. But that's just my playstyle.
The last level was a pain just because it was one level more to go and just wanted to get it over with. Leveling without rest bonus sucks as well especially when you been through the content before also. But I'm finally glad to be done with leveling up my DK for now and maybe can do more fun stuff with him when I have the time. Only profession he's skilled in is Master in Inscription and First Aid, everything else is at lvl 1 so that's allot of work to skill him up.
Have yet to decide on another profession for him. More less can't decide really. I'm not one to like heavy crafting professions, I tend to prefer gathering overall vs heavy crafting professions. But Jewelcrafting have some appeal and I don't have a alt that does that. So that have some appeal. Overall lots of loose end stuff to do on him let alone put him in some semi decent gear when have time.
Only real thing I found slightly interesting leveling my DK is their self healing ability. Funny almost all the classes I play have some form of healing yet I don't practice the art of being a healer in any real fashion. But leveling up my DK I barely used Bandages or had to eat all that often to regain health unless soloing something difficult. I just ran off found a mob and Death Strike it back to full health often vs Bandaging or eating. When I leveled my Paladin way back then, eating and drinking for mana was all too common as well as using a ton of Bandages leveling up. Much different leveling a DK mechanic wise.
After learning and skilling and learning DK mechanics to some degree leveling up I think I can enjoy playing a DK to some degree vs letting him sit in a corner gathering corpse dust..... again. DK's are a very easy class to play right out the box, but can seem a more challenging time to master play properly mechanic wise. I still prefer playing my Paladin vs a DK. But Shamans are fun and enjoy playing a Shaman more than I enjoy playing a DK. All different play styles. One of those is going to win out eventually.