With three roguish guys (the PCs, not the players), I'd just worry about so many people with trapfinding and that overlap. A few questions and suggestions:
I'm fine with three rogues as long as they agree not to get fed up and backstab each other. There are just so many mechanical options to fit the concepts, it seems like we can work it out without anybody feeling short-changed.
For the Martial Rogue, would he be built on ranged or melee combat? If melee, are you interested in the swashbuckler?
For the halfling thrower, do you have your heart set on rogue? It can be tough to consistently sneak attack with ranged weapons at low level. Could the concept still work with him as a ranger, fighter, or bard? The Ranger Combat feats would work as long as he had Quick Draw. I'd be happy giving everyone an extra feat at 1st level so that you could take that and pull this concept off.
Max, I'm digging the barbarian, but cleric will be the back-up plan.
The straight rogue and wizard should be fine.
Only, a dwarven druid is great. Is he an underground, stone-worshipping type, or an against-the-grain, trees-and-animals type? Either one is fine.