Children's Week (ID 10942)

As mentioned, this requires level 60. It's a bit hectic a quest line with it but doable at 60 too. Something to note, on almost all legs of the quest, there's a small event that happens. The Azeroth Children's week quest can have some events completed simply by walking to where you need to go, and then summoning and finishing the quest whenever. The quests for this set requires the event goes through. Now, if you happen to have someone doing the quest ahead of you, the event may stall. Usually resummoning and running around till your Orphan continues it will fix this.

The steps, for the horde quest:

• Summon the girl with the whistle, and accept all three quests.
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• The Throne of the Elements. (http://www.wowhead.com/?quest=9870 ) The closest location to you to go to is the Throne of Elements. Summon the girl near the fire elemental and an event should trigger. Turn in the quest to the nearby questgiver, Sharvak.
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• Hch'uu and the Mushroom People (http://www.wowhead.com/?quest=10945 ) Head to Sporeggar. There's a particular Sporeling guy she activates the event on, Hch'uu, he's somewhat smaller then the other Sporelings. Head near him, and he should be good to turn in that leg of the quest.
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• A Trip to the Dark Portal (http://www.wowhead.com/?quest=10951 ) Head to the Dark Portal. Head to the Stairs of Destiny, and moving around the large platform between the stairs and the portal a bit should cause the event to happen. As of this year, it doesn't appear as if a soldier spawns any more. Still, if you're having any issue getting the event to start, run up and down the stairs with your Orphan summoned out till she kicks off the event.
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• She gives you two more quests: the first ("Now, When I Grow Up...", http://www.wowhead.com/?quest=11975 ) is to go to Silvermoon and bring her to see the L70 Elite Tauren Chieftains, located just right from entering the main entrance into Silvermoon. Just move around below their location under the balcony, and a small event will happen and you'll be able to turn in the quest.
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• Last quest ("Time to Visit the Caverns", http://www.wowhead.com/?quest=10963 ) before turnin has you going to the Caverns of Time, first to their Quartermaster (Alurmi, http://www.wowhead.com/?npc=21643, located partway up the tunnel normally bipassed by flying down from the top) to buy a toy dragon (90s, 1g if not honored) and then to the large dragon on the dias. Again, a potentially interuptable event, but just run around the base until he reacts to your orphan, and turn in the dragon to her to finish the quest.
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• Lastly, you're sent to back to the Matron Mercy in Shattrath to complete the quest, noted here: http://www.wowhead.com/?quest=10967 ("Back to the Orphanage")
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  Each quest turnin was worth 12650xp at level 62, and roughly 7g 60ish silver at level 70. Six turnins, including the last one, all give the same XP/gold. Each quest leg gives 250 Lower City rep, except the final turnin, which gives 500.
  
  edit: updated for this year's minor change to the horde events.

I did the followup quests in this order:

Visit the Throne of elements http://www.wowhead.com/?quest=9870
Nagrand 60.7, 22.1

Hch'uu and the Mushroom People http://www.wowhead.com/?quest=10945
Zangarmarsh 19.3, 51.3

A Trip to the Dark Portal http://www.wowhead.com/?quest=10951
Hellfire Peninsula 88.7, 49.9

(the dark portal quest didn't complete the first few times I summoned the girl. The last time I summoned, I was standing at 88.7, 49.9, and the quest completed immediately.)

At this point, you can accept two more quests, and do them (in Azeroth). I flew back to Shattrath and portaled to silvermoon, to save my hearthstone.

When I grow up... http://www.wowhead.com/?quest=10960
Silvermoon City 86,37, then follow the kid into the basement of the building.

Time to visit the Caverns http://www.wowhead.com/?quest=10963
Tanaris, in the caverns (entrance is at 65, 49, buy a toy dragon from the quatermaster: 63, 57, then walk to the giant dragon in the middle: 60,54 and he will judge the child. Give her the dragon to complete the quest.)

When you are done, return to Orphan Matron Mercy http://www.wowhead.com/?npc=22819
Shattrath 74.8, 47.8

This quest requires level 60.