AoE grinding is incredibly fun. I went ret till level 40 then AoE grind my way to Outlands. Lv 50 is one of the best levels to AoE grind. Head to Sorrow Hill in Western Plague lands and just kill the packs of undead there. Gain about 4 levels just kill those packs of mobs and helps you acquire AD rep (not like you need it anyway)