The Alliance wants you... to quest in the Southern Barrens!

That's precisely what I've been doing. It's a great zone, really, much better than the old Barrens horde-side.
First off, you have several factions, Stormwind, the Earthen Ring, Cenarion Circle, Ironforge, and even a bit of Gilneas. Yay loads of rep!

Then you have the zone flavor. An embattled Alliance is fighting both against the Horde and against Nature itself. How cool is that? You have quests to, among other things, go save an ambassador, capture a hill for the Alliance (which isn't as easy as it sounds), get supplies, burn down catapults, save people from a burning building, and trust me I could keep going. Want to know what happened to the Tauren village outside Mulgore? Well, you got to find out.

And I just want to keep questing there. I've already gotten the quest achievement, but the storyline isn't done and I want to find out how it ends. That, more than anything, impresses me. I want to know how it ends, even if it isn't a good ending for the Alliance.

I wish I could tell you more about it, like the one questline that seems so ho-hum, until you get into it and it turns so epic, but I don't want to spoil it for you. Just go do it, preferably on an alt of the proper level (30 to 35ish). Anput hit it at 30, which was about right, and she's now 36 and is a bit overlevel for the last bit.