I am a big fan of classic literature and the idea of assembling some of the greatest literary characters together is a great idea, at least in my mind. While the 2003 film adaptation of this series was anything but spectacular, I still watch it occasionally. I'd love to see them try it agin, though I doubt that would ever happen. With out further ado, here is my cast.
Jeremy Irons as Allan Quartermain
Natalie Portman as Mina Murray/Harker
Naveen Andrews as Captain Nemo
Billy Boyd as Hawley Griffin/Invisble Man
David Tennant as Dr. Henry Jekyll
For Mr. Hyde, I think they need to go CGI. In the 2003 film, they put Jason Flemying in a rubber suit with arm extension and I don't think it worked out too well. I think David Tennant should still do the voice, just add some distortion to it.
I liked that they added Dorian Grey to the film, as he is one of my favorite literary characters. Ben Barnes as Dorian Grey
Robbie Coltrane as Campion Bond
For the villains, I like the idea of James Moriarty, they just need to use him as more of a "master-mind" villain. Bill Nighy as James Moriarty
And since we are using the arch nemises of none other that Sherlock Holmes, why not include him, something smaller though, like in a flash back of sorts. Sir Anthony Hopkins as Sherlock Holmes
On to the main villain. This dude is ruthless and to this day, they are unsure of his identity. In order to darken this series up a bit, I think he's a perfect fit for this group.
James Caviezel as Jack the Ripper
There you go. I know this isn't a very popular series, but I love the idea and was sad that it was basically ruined by the 2003 film. Here's to hoping for another!