I think Clive Owen projected a lot of Sandhurst's wounded psyche and exhaustion in his role in Children of Men. That sense of his being worn down by life came across well, though physically Owen is larger than Sandhurst by about five or six inches.
Roxanne Dawson would be closer to my image of Ramirez than Rosario, but Admiral2 had a Latina model/actress in mind for his My Way series that I thought was a dead ringer for Liana, only I can't remember her name!
Patricia Velasquez as Isabel Montoya.
Starkers is also using her as his ship's captain (but he can't find a decent picture of her

[tee hee]). Or are you thinking of
Michelle Rodriguez as Gwendolyn Flores? If it's Velasquez, gotta disagree. I don't see her as Ramirez at all. But you would know best obviously.
Liev Shreiber is an interesting choice for Lar'ragos, though I'm not sure his body-size and hair are right. He does have a time-worn look about him, despite being relatively youthful, however.
I just didn't want to be one of the numerous people jonesing over Malcolm McDowell. (PEOPLE! Just cause he played an El-Aurian don't automatically mean he's right for the part! You might just as well cast Whoopi Goldberg!)
As for Pell, I'd have to defer to
DarKush on that one, as he originated the character.
Someone said Ali Larter, but since I left the post I've been thinking
Olivia Wilde (House, MD)
As for Akinola, here's my thing:
I'll just say this, repercussions or not. I'm the type of guy that thinks if you're going to cast a character, the ethnicity of the actor should match the ethnicity of the character. It's just common sense to me, and it's kind of a personal bugaboo of mine. For instance, the one thing that grates on me about
Scarface is that it's supposed to be about Puerto Rican mobsters and ain't none of the main characters played by
Puerto Ricans! Another example, Halle Berry - the
least African woman I can think of - being cast as Storm in
X-Men, a character that is clearly from Africa, not California. And Jessica Alba playing Sue Storm gives me nightmares at night. (You people
seriously couldn't find a young, white blonde girl in
Hollywood that would help you sell tickets??

)
So with Akinola, I want to cast someone who's really
African, or who at least looks African. I don't want to just plug in any old African-american, which is why Morgan Freeman and Tucker Smallwood don't fit for me. I think in terms of Ejiofore and
Djimon Honsou - again, too young - or guys like
Yaphet Kotto, Blu Mankuma, or
Ron Canada - better for looks and age but all too chunky, last I saw of them.
So there's my dilemma. Make of it what you will.
And while I'm on the subject:
captcalhoun, dude, really, not to knock your taste in women, but no way in hell is Lena Headey right for Bobbie March! Not because she's pretty, not because she's not butch enough, but simply because even if you taught her how to speak every American English accent ever, there's no way she'd come across as someone who used to be a
southwestern American farm girl who learned to shoot on her sniper daddy's big ass rifle! That's how you wrote her. That's not Lena Headey. If you must go the Sarah Connor route,
Linda Hamilton is a much better choice, but really, you need a young American woman with light hair that still has freckles. (I don't see why you don't use
Jennifer Garner! You like her, dontcha?)