Honestly, I think a Paladin is the best class to farm instances. They have 0 worries - armor, AoE (not as good as mage, but enough for farming), bubble/heal, and they can rez lowbies that you are taking through.
Those are all just conveniences though. Mages are awesome for farming too.
Here is something I just posted on the main Forum page:
Quote:
An important note on running lowbies through instances - tell them to do abosultely NOTHING. If you are gathering up mobs, and they do 1 heal, or 1 hit, or cast some spell, then they might aggro mobs and die immediately (30-50 elite mobs pounding on a lowbie = instant death). I don't know how many times I've had to rez lowbies that I'm running through because they want to help.
Also, if they want to watch you kill a million mobs at once, tell them to wait in one spot. Then, you go gather up mobs and bring them in front of the lowbie. If the lowbie tries to follow you around, they may aggro some ranged mob (since that mob will not be running after you in melee range)...and die.
These will make the instance much more fun. If your lvl 70 can rez, then it's not too bad. If you can't, then it's annoying to wait for the corpse run.
Oh, one last tip would be to have the lowbie take off armor. So if they die, they don't lose durability. Not a big deal, but just a tip. That may also be enough reminder to them that they need to stay out of the fight.
I hope that helps.