If you are just boxing teams of two then using the Dungeon Finder to level your teams up is really, really fast. The easiest way to do is just spec both as DPS (the ques are a little longer but still not too bad.) This works great all the way to 80. I usually stop and quest a little at 68 to get some WotL gear in Borean Tundra. All of the starting quests in that zone are very boxer friendly. Using this method you are looking at less than 24 played hours to get your duos to 80.