I first tried out Archaeology on my druid, right after the expansion hit. Despite the nice little hits of experience every time she surveyed, I quickly grew antsy about completing the new content. And left her Archaeology hovering in the low 100s.
I tried out archaeology again on my undead shadow priest, using it to pass time between dungeon queues. But the PUGs for my horde battlegroup were uniformly horrible, so that didn't last long either. I think she may have just barely hit 100.
Fast forward to my gnome mage hitting 83, and my not being enthusiastic about pushing a 4th character through all the Cataclysm content again so soon. Dutifully, I headed over to the archaeology trainer, then set out on my flight path to my first dig site. And this time, it stuck. I spent hours zooming from place to place on my mage, herbing as I went. Racking up the experience. I got my first rare pretty quickly-- the Fossilized Hatchling. At which point I started to get the crazy gleam in my eye-- oh yes, Vial of the Sands, one day, I could have you!
And the rest, as they say, was history. I kept at the archaeology, and hit 525 with it not too long after the mage hit 85. Almost all of it just from surveying dig sites.
And no, I don't have the Vial of the Sands yet. But I know if anyone can extract that from the Uldum sands, it's my lucky little mage.