I would just summon em all to one spot, do the first few kill quests there, get as high as you can go, then log out one toon, create a new toon in that has a starting place that you haven't done with this team yet, and summon yourself there. Do as many quests as you can while you are there, and repeat if necessary. The summoning feature makes it trivial to move around quickly. Once you get high enough, you can move to the next zoneand keep repeating. As long as one account has one toon in an area which you want to get to, you can always insta summon yourself there. Imagine doing this in Duskwood for Alliance. All that running back and forth between Darkshire and the graveyard.... you could probably ding a few times just from that! I'm sure there are tons more of those quest chains where you just run back and forth a lot. If you get creative you could make it into an art form