Some efficient ways of leveling 20 characters at once (Horde side)?

[dustofoblivion]

I just finished leveling my future ZG/AQ20 team to lvl 30, and I did it by group of 5 characters, basically repeating the same leveling process of 'farming dungeons with some questing on the side' four times. I was just wondering if you guys had some creative/out of the box ideas on what I could do to speed things up moving forward. The XP raid sucks; farming dungeons in groups of 10 has not yielded very good XP.

Although I'm not sure team comp matters that much, the team is:

1 Warrior
1 Hunter
1 Druid
2 Shaman (Resto/Ele)
2 Priests (One Disc/Holy, one Shadow)
5 Warlocks
8 Mages

Thanks in advance for your input!!