I agree that Northren isnt as good for Multiboxing. I have been slowly grinding my way to 80 on my Pally/Druid pair. I have been doing gathering quests because i need the xp, and its not too bad with only 2 toons. And to comment on /follow issuses, follow strobing from Jamba works just fine in all the vehicles i have been in so far. I beleive this is because it is targeting the toon, not the vehicle. My guild has used this same idea to make the Malygos fight easier, targeting one of the other players who takes care of the movement, while the rest of us nuked the boss. If i were fiveboxing, i think i would still level with quests. i would think that you would be getting more gold, which is never a bad thing, and is quite useful if you dont have your epic flight yet. Although if you want to skip some gathering quests, maybe look them up on wowhead and see if they are part of a chain, and if not, move on to something else.

just my thoughts!