Locks are good to have, and for team 2 after I got over 20 the druid is a killer healer. I have for team 1 'The Soozan's' 1 Holy Priest, and 2 Locks, I always forget to SS the priest since I am having fun killing everything around and dont get killed often with regular mobs its the 70 horde with PVP gear that love to gank me. Second team 'The Coyolxauhqui's' consist of Druid healer, x 2 mages. I have a pally, hunter and shaman waiting at 70 and they might join the team on some runs, I use them sometimes but mostly I do stuff with just the teams vs. going in with my 70's since my main will not be able to do it cause the 70's are on the healer account.

Have fun play around for a bit and you will come up with a good combo. As mentioned its all about what that other member will bring to the team.