Just did a Quad of shammans from 33 to 60 last weekend. /played was 44 hours on the new accounts with some down time while I was afk, it all seemed to blur together (all have 300 or very close FA). A mix of quests and instances (w/70 pally tank with crusader aura for grabbing FPs) seems to be very efficient to me. The altar event in ZF was crazy nice, only wish I could reset just that part. I found that the sweet spot for me was yellow / orange quests with no booster needed. Also don't forget to burn some of that old junk (if you have it on another toon) for the Argent Dawn turn quests at Light's Hope. Key zones I will hit again with my lock team, Felwood, Un Goro and WP, both handed me big chunks of exp with only a few quests (3 hours per zone or there abouts). Remember to grab all those silly power crystals in Un Goro (7 each color, per toon), the resulting ride around quest is a nice batch of exp.

I meant to do the Searing Gorge kill quests but never got near there until I was already higher level. Did not quest in Westfall, Redridge, Duskwood, Desolace, Stonetalon, Swamp of Sorrows, Blasted Lands, Ashazara, Burning Steppes, Barrens, Ferelas, or Thousand Needles except to get key flight paths in some. It was a different game.