Bill Nighy for Q. End of story.
And Jeffrey Deaver made a great suggestion for Mary Goodnight (who is Bond's secretary in several original Fleming novels, not just the one-off Bond girl of Man with the Golden Gun, and returns in Deaver's Carte Blanche) - he describes her as looking like Kate Winslet.
I've nothing against Naomie Harris as Moneypenny, but I had my fingers crossed for Christina Hendricks. (Remember Lois Maxwell was a Canadian, so there's no rule that says Moneypenny has to be played by a Brit).