I have two 70 druids that I box occasionally. As a team they are really only good for stealthing to bosses in instances or farming in instances. In PvP you need to change forms constantly and kite alot so it doesn't work too well, at least mixing feral and resto. Two moonkin is okay.

Pet classes make great leveling companions for druids. I leveled one of my druids with a hunter and the other solo. When I was with the hunter it was pretty easy. I had one button that put up hunters mark, sent the pet in and put a heal over time on it. Roots is another big factor, on mobs there is no diminishing returns so you can just keep a mob rooted while the hunter kills it.

This would also work really well with a warlock. Better even there is pretty good synergy between warlock/resto druid as evidenced by 2v2 arena ratings. Voidwalker tanks, warlock dots and nukes, druid heals voidwalker or roots stuff for the warlock to nuke. Pretty easy.