G.I. Joe Live-Action Movie!

[Kai Lord]

And if any romance is in the film, it better be between Snake-Eyes and Scarlett like it should be (and originally meant to be).

Yes but only if its the tortured "never meant to be" variety.

As for the cast ideally they'd go with unknowns but if I were to hire established actors I'd probably start with:

Scarlett - Love Milla Jovovich but somehow she doesn't seem right for the part. I'd go a little older, probably Famke Jansen or Naomi Watts.
Duke - Russell Crowe
Lady Jaye - Demi Moore
Snake Eyes - Guy Pearce (before the mask)

Zartan - Sean Bean
Destro - Michael Dorn
Storm Shadow - The bad guy from Romeo Must Die
Crimson Guard Twins (Xamot/Tomax??) - Colin Farrell
The Baroness - Angelina Jolie
Dr. Mindbender - Daniel Day-Lewis
Cobra Commander - The guy who played Kraven in Underworld (just kidding)