Wintergrasp, when your faction owns the zone, is the king of farming locations. There is an endless supply of elementals, and there's a load of ore and herbs of the gatherers as well. Every single type of Eternal can be farmed up here.
Looking at these maps, the colors used to circle farming areas match up to the type of elemental you'll see. Brown (or Grey when necessary) is Earth, Blue is Water, Light Blue is Air, Red is Fire, et cetera.
Not marked on this map as the Earth and Water elementals, because it would just be a huge circle around the entire map. The entire center of Wintergrasp is full of earth and water elementals.