Here's a little background.

I generally don't run any instances because I'm on an East coast server but I'm West coast and play pretty late. Guild runs and PUGs are hard to find.

I already have the following toons (close to 70):
Hunter
Rogue
Priest
Warlock

The classes that I would like to play are:
Mage
Paladin
Druid
Shaman

Would this combo work for leveling and for going through all (or most) of the instances (up to level 69)?

1x Paladin (Tank)
3x Mage (DPS)
1x Druid (Healer?)

At 70, I could swap out toons if needed with the toons that I already have.