Rather than go for a purely action-movie stylized cast, I'd rather see a movie that brings out the true nature of what it means to be an adventurer, a more mercenary style-group, one with actual intra-party conflicts. It would never hapen, but I would most certainly watch it.
Rogue: Eliza Dishku, After seeing her work in Bufy I can say that she could play a character with real git that would not just be a pretty face, although that face is pretty. I'd reallly like to see someone that could be adept at moving around social circles, despite misgivings about who they have to work with. If not her I'd put Benecio Del'Toro here, but I have another role that I think would fit him more.
Sorcerer:Benecio Del'Toro, Like I mentioned before he has git, but he also displays an amazing level of intensity, and a lot of his work has showcased characters with a lack of care for social conventions. Beyond that, I believe he could bring a real dangerous presence that I feel would emphasize the place Sorcerers hold in standard D&D campaigns. Most likely he would feel repressed by the fellow members of his party and be able to display the cool rage evidenced in that movie with Tommy Lee Jones.
Barbarian: Brad Pitt, After seeing Fight Club and most recently Snatch I can hardly see how anyone else could capture the sufficient amount of rage I'd like to see in any Barbarian that made it to the stage. As far as I'm concerned you need more than just a big guy for this role, it requires the portrayal of near insanity. I would again offer Twelve Monkeys as evidence of his propensity here. I also like the fact that he and Del'Toro worked together on Snatch.
Cleric of St. Cuthbert: Peter Norton:Another actor able to justify a level of psychosis in his characters, Norton can play detached and loyal amazingly well, something I feel is neccesarry to explore when dealing with the feelings someone who talks directly to their god would develope for their fellow mortals. He would also be able to express the subtleties involved in split loyalties. I would go for a character that felt strongly about justice, but more than willing to sacrifice others in this pursuit.
I tried to bring in some twists, but keep the party pretty typical. Mainly I've tried to cast in the vein of recent comic adaptions, bringing in those who could handle action while still keeping their characters to the forefront.
As I am fairly new to these boards I'd like to say that I'm pretty impressed with the objective discussions on EN World, I have to say this is probably the best-natured out of any group of people I've seen online.