I've got more than my fair share of alts, and I like to think I'm fairly proficient with leveling characters. So I had an odd thought on the subject playing messing around on my 64 holy priest last night
It's about cataclysm (of course) and how blizz did so much right and then so much wrong. Terathis was created and leveled entirely in cataclysm content so that I could have an alliance character on my main horde server, and I had a blast leveling him, until I hit wrath content. Cataclysm was REALLY a struggle to get through.
You see, leveling up to 70 is so much fun. You have so many options for how you want to level. You can quest of course, but even then you have 2 entirely separate continents to choose form, and you can bounce back and forth between them if you want. Even for starting areas, you can always go to a different races zone if you don't mind a run or have a friend with a 2 seater mount. Slightly slower than questing, you can level almost entirely through dungeons if you want. Or through battlegrounds. Or from gathering and archeology if you really want to. In Wrath content, even with the buff to experience you really hit a stumbling block in speed, especially when it comes to instances. Add in the poor item drops for wrath normal dungeons and you're pretty much forced to switch to questing.
AT least in Wrath, you have options. Howling Fjord or Borean Tundra. Maybe both? Hop around, skip some quest hubs, do whatever ones you like. You have freedom in the questing and the zones, so much that you don't have to follow the same path twice if you don't care to. Then you hit 80, and you lose all semblance of choice.
Oh sure, there's 2 starting zones, but both of them are ridiculously linear. They're a BLAST the first time through, holy crap are they ever fun! But they lose the fun factor by the third time through, and become a chore after that. You do the same quests, in the same order, and you can't skip a single one because it's all phased. The story element is strong, and you experience the progressing story, but it's more like you're along for the ride instead of choosing how the story progresses. And dungeons offer little relief, they take a while to queue for but more importantly they offer little experience after you do the quests the first time through.
Choice, that's the key. Rather, the illusion of choice. You need to feel like you're deciding your character's path, like you are in control of your own destiny. You have that in the lower levels, the choice. The options. It's fresh and fun and any monotony is easily broken up with a dungeon or a battleground, both of which offer fairly significant experience gains.
Unlike my issue with the rest of the current endgame, the problem here is not time. It doesn't take very long to get from 80 to 85, possibly even less time than 70 to 80 takes in fact. An afternoon can easily net you a level or 2, and that's most of the job right there. Again, the problem is lack of variation. Aside from the choice between Vashj'ir and hyjal, you do the exact same zones in the exact same order, doing the exact same quests.
I have high hopes for Blizz. They're not stupid people, far from it, and they keep changing things trying to get it better. We'll see what the future brings.