I did Highmountain and val'sharah or whatever it's called. I got through both and did the zone end quests without much of a problem. Most of the quests phase you together. However, in highmountain there is a quest that wants you to accompany ebonhorn into the deathwing cavern thing. This quest is special because it gives you followers per character, and with 5 of them you can get 500k extra dps. I ran a loop around where the elite etins are outside of the cave, and was getting a level every 35ish minutes grinding them with rested experience and heirlooms. You can grind here till 110 too.