Casting has again been excellent, but I'm not too sure on Stannis personally. Melisandre though is perfect.
GRRM apparently directed the Blackwater episode (which also took up most of the season's budget
) so that should be amazing.
Something which happens next season (if you've read book 3, you'll know what I mean) has the potential to be one of the great TV scenes if they do it right, which I'm sure they will.