There's a Classic achievement for this one and it's also part of a larger two-part achievement that awards the Argent Champion title called The Argent Champion (go figure).
Right now I've discovered this much...
Start at Fionas Caravan in Eastern Plaguelands at the road leading into it from Western Plaguelands. The caravan is basically a linear quest line through the entire zone. There's a lot of quests here - as a matter of fact the zone achievement calls for 70! Which is the single highest number of quests in any zone in Eastern Kingdoms (Darkshore in Kalimdor has 90 and Ashenvale also has 70).
When you get to Light's Hope Chapel there will be a quest called The Trial of the Crypt. Once you complete it you will unlock two repeatable quests. One that leads you to Scholo and one that leads you to Strath. I'm not going to tell you which one to do - but the Strath repeatable is by far and long insanely easy.
Here is the list of the quests leading to Trial of the Crypt (spoiler to save room):
Spoiler:
Clear the monsters etc. to Balnazzar. Opposite Balnazzar is Instructor Galford. Kill him and take the book from him, which was behind the table. Here is the location of the book: Annals of the Silver Hand
Exit the instance, go to Plaguewood Tower. DO NOT RESET THE INSTANCE! Turn it in, get 2000 Argent Dawn rep.
Grab the quest again and do the same as before. Because you didn't reset the instance, there will be no mobs to kill; making a clear path for you to follow. The book is still obtainable.
To get revered to exalted you will need to do this quest 11 times.
On a side note:
After revered it seems like the quests don't provide much in the way of rep for AD. There are a few here and there that give maybe 350 rep and there are some mobs up in this area that give between 5 and 10 rep each depending on your guild level and your race. If you want the achievement for clearing the zone - go for it, but I would not recommend it as an alternative to doing the repeatable.
