In vanilla WoW the most enjoyable part of the game for me was class specific quests. The low level rogue quests for lock picking and such were so fun, even if menial. Finally earning my Rhok-delar on my hunter at level 60 was the most memorable moment in any MMORPG I've played (Even more enjoyable and rewarding than earning the Deathwing Legendary Daggers on my rogue lol, though daggers took longer). I would love to have class specific max level quests with an extremely hard degree of difficulty. Anyone have thoughts/opinions they'd like to contribute to this?
I don't know how the class system really works in this game though... seeing as how you choose a guild or w/e for your skill line? So maybe something like this wouldn't work out too well.