I started 2-box and as soon as I got my paladin to 60, I did Outlands with my 60 prot warrior at the time.

But I was also running a prot paladin, so I re-spec to arms warrior and it was great on questing as my prot pally just wont die, and my arms warrior help kill things fast.

There was no keyclone at the time, so I was 2-boxing old school style with 2 keyboards and 2 computers.

Nowadays, my 70 warrior rots and have been replaced by a 70 resto shaman. My warrior is a BS/Miner so he's good for something.

My paladin is still prot and active.