I don't do a lot of wPvP, but in recent times I've had some really cool wPvP in Arathi Highlands where the rare Ogre is. Usually you can find 1, sometimes 2 or more lvl 20's sitting in that cave, waiting for a bruising.
A week or so ago, I was having some awesome fights on my Huntard taking on 2 x Ret Pali's. And a week earlier, I stumbled across a Fury on my Prot, but after he handed me my backside in Prot spec, I obliged by switching to Fury and we just went for it.
After I got the upper hand, he even disappeared for a while and invited his lvl 85 friend to the party......... unfair....
The cool thing about that place is it's only serious twinks that farm the rare, so you're guaranteed some cool fights.
But my rules for wPvP - if they are lower level, only attack if they start it.
If they are equal or higher level - it's open season........