You Are Rakh'likh, Demon quest chain

You Are Rakh'Likh, Demon is a very long quest chain connected to the Blasted Lands. The initial quests for the Blasted Lands chain differs by faction, but the majority of the chain is neutral. This quest line gives a large amount of experience (which translates to gold as a level 60) The completion of the first 19 stages of the Horde side chain (Fall From Grace through Return to the Blasted Lands) nets you over 49 gold (assuming lvl 60 xp to gold conversion) as well as a mana/health regen trinket and a weapon used for completing the quest line (sells for additional 5g). The final portions cannot reasonably be soloed although decent soloing classes can solo the first 19 stages in 2–3 hours (the elites in Kirith and one of the Name of the Beast quests can be a challenge)

While most of the action happens in the Blasted Lands, it will send the adventurer to Stranglethorn Vale and Azshara as well. You'd do well to either have some help or be 60+ when getting to the Azshara parts of the quest chain.