Well, wouldn't that be something.
I'm Team Aniston, so I haven't been a big fan of Pitt and Jolie lately, but I gotta admit I think they could go a long way toward pulling off the romance in that story (although, I haven't seen "Mr. & Mrs. Smith," so for all I know, they could have no chemistry). But they both give off a very self-possessed, strong, independent air on screen.
But I never pictured Dagny as ostentatiously beautiful as Jolie is. Beautiful, yes, but more understated.
UPDATE: N.Z. recommends "Mr. & Mrs. Smith" and assures me there's chemistry.