I actually agree about Alec Baldwin in his Jack Ryan days...he would've been more low-key than my mental image of Calhoun, but I could see him doing an interesting take on the character.
I still don't like Mel Gibson, for much the same reason you don't like Downey... his version of the character 'feels' wrong to me. Maybe we just have really different mental images
Oh, and The Rock and Bell are both really far off, I think. I love Vosloo as Cwan more and more, the more I think about it.