I personally love balance druids.
But am not sure if two of them is enough to burn things down at range.
I'm running five together, and most things don't need a second nuke.

With two cat druids, you'll put out very strong dps.
And have talents to heal slightly on a melee crit.
And as cats you'll crit a ton.

Moonkin/Caster or Feral/Cat, you'll level a lot faster then as a Bear.
But Feral/Bear will get you to the Feral/Cat stage, if you want to go Feral.
And a Bear is an excellent option for tanking down the road.
You might consider dual spec for one toon (Cat and Resto) and the other go Cat and Bear (one spec).
Possibly two sets of gear for each, Bear/Cat and Cat/Resto.
But that is down the road.