Today we have the Lower City Reputation rewards that are aimed to Alchemists, Tailors and Jewelcrafters. Classes that get benefit are Warriors, Druids, Paladins, Shamans, specially Priests.  There are other general rewards that everyone could use. Just remember that to enter Kael’Thas dungeon and Caverns of Time: Mount Hyjal, you need the Auchenai Key available at revered with the Lower City to complete the quest from A’dal, which requires you to kill Murmur in Shadow Labyrinth(Heroic-mode). Check out the 16 rewards.