I levelled 70-80 by questing the various zones and ended up dinging 80 by shalozar. This left Zul'drak, icecrown, and storm peaks completely-unquested, and about half of shalozar, and that turned out to be worth about 5Kg per toon iirc. In fact now that I think about it, I haven't even done Zul'drak on my shammies.

Definitely do Borean and HF before you ding 78, as the level 70/71 quests will grey out at 79/80. Grey quests don't pay very well.

Edit: I never used up all the rest on any of my toons levelling, this likely helped a bit.