I level my Warrior as prot. Hes currently 66 with around 10k health, I can easily take 5 mobs and take more then 50% of their health with one revenge crit. Shield block and peew peew, easy as hell.
I wanted a be an end-game tank as well so i leveled my warrior as prot to get the hang of it earlier and learn the abilities, i leveled her up before LFG so almost all through questing. I think it goes without saying that rolling prot if you intend to level through LFG is pretty much a no-brainer due to the supply/demand, though i'm sure a few people will disagree. I wanted to switch it up a bit, so i dual-spec'd Fury to give it a go, and although it was a nice change of pace, i found it less efficient than prot because (1), if you pull more than 2 or 3 mobs you might have to run away which you usually would aim for with prot, and (2) because around the time i hit Northrend, i found it difficult to connect with hits a lot of the time with TG due to the low amount of hit on gear. When i would hit it would destroy mobs, and WW is nice, but sometimes i would just RNG-miss a lot and it would kill my rage.
Prot is the way to go IMO.