multi class choices help for boxing newbie

i've searched around & haven't found any guide to what class combo's work out, why & the like, so here's my question.
i've got a 37 frost mage that im planning to join three others i'm planning to box, one of them will be a priest but the other two idk what would
of the other classes i would choose, in order of favor: hunter(be), shaman(troll), druid, warrior(no race pref,maybe orc), warlock(no race pref)
the talents for the two & the priest are all up to your opinions

this would be my first time boxing, i know its best to have same classes but im willing to go through the headaches to do different ones
i'm planning on all four on the same comp, using autoit for the hotkeys, my own window management & not a multiplexer, though i probably will need one, i'll find out when i get in game with em all :P
also where would be the best lvling location, to start from? i can get them to the main horde cities SM,UC,Org,TB fairly easily & have made undead & be 15+, so i know the quests & area for them the most.

i know you get these kind of questions all the time, sry & thx about that, but there should be a wiki or guide of class choices somewhere.
edit: i have no intention to pvp, though that might change, though it would take a while to lvl up

When boxing I like to consider the utility aspect of the group as well as what each individual can bring to the whole.

I would prob go for the druid/lock or shaman/hunter combo. Both give wipe recovery (lock can SS the priest, shaman can self rez), both give utility (MOTW buff, boomkin aura, synergy of lock w/shadow priest, or totems, backup heals, aspects, off tanking thru pets).

Ultimately it would come down to personal preference.

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.