Ok, so here are some thoughts.

5 Shaman = No tank. Heroics are *possible* but not a very easy path, without a real tank.
5 Druids = Possibility of Tank + Either 4 DPS or the Tank/Healer/DPS route. One thing to keep in mind is that you won't have much CC with an all-druid group, but druids are also OK at holding aggro on multiples, so it might not be a problem.

Now, the folks here (collectively) have a lot more experience with Shaman teams and Shaman+Tank type teams, so you may find or hear a lot more advice steering you towards shaman. I think 5xDruids offers a lot of potential, particularly since you can quickly HoT up a tanking druids with a lot of healing and then nuke away. While I don't have firsthand experience, I would think a Feral Druid + 4xBalance druids could be very potent. Moonkin doesn't stack, and eliminates the easy healing option, so I'd be inclined to stay out of moonkin form and simply work in some HoTs with my nuking rotation on the four druids every 10-15 seconds. That would certainly serve you well for normal mode instances, and may be OK for some heroics. Not having a dedicated healer means healing aggro would be spread around more, which may help your swiping Bear tank hold aggro a bit easier. Just some theorycrafting...

The 5xDruid has a lot of potential and probably wouldn't get stale-- you could eschew doing heroics for a while, spec them all Boomkin, and tear up BGs. 5 Stealthing Kitties would be fun in certain situations where you can effectively attack an AV graveyard with a LOT of force all by yourself. Make sure to buy a PvP trinket, since fear will be a bigger problem for the druids...

For your goals, I'd recommend either the 5xDruid combo, or a 4xShaman+Tank (and Pally makes the most sense here, in my opinion) type setup.