I am trying a different approach.

1 ) Level my tanks individually to lvl 85 and gear them properly.
2 ) Discover instance entrances with the other toons and level them instancing.

So far I have leveled my tanks almost 100% instancing. After I hit lvl 85 I did the hyjal quests... all of them for the gold and reputation. Other than that, my tanks have only the portal opening quests from the other zones... don't think I will do all the quests there because phasing and cutscenes are just boring.