Horde guide states:
Stranglethorn Vale: Alliance dread STV. It should be horde territory. On my Alliance guide I don't recommend coming here, but on this horde guide, go for it! Get from 30-40 with no problem at all.(Unless you're on frostwolf, according to a few players ally gank stv on frostwolf.)
Tanaris: Once again, a spot that Alliance players avoid, way to many horde for us. Enjoy the free honor while you're here! :D
Alliance guide states:
Recommended: Stranglethorn Vale (STV) (30-45)
Recommended: Tanaris (40-50)