pally has decent aoe tanking ability.
druids have good mana regen and decent spells for balance as well as resto. do mostly balance with some resto.
get moonkin form for 5% spell crit buff. im sure the pally can benefit from this too.
in a bind, both moonkins can shift out and heal, reshift to moonkin and dps some more.
overall, you'll have great aggro holder, great dps, and a handful of healing options, not to mention rez for all. druids get an in-battle rez that's invaluable.