If you are foolish enough to be contented, don't show it, but grumble with the rest.
Harrison Ford - one of my favorite actors - has a wonderful sense of character and depth and uniqueness to him, yet he's able to just deliver the lines without putting any English on it.
Whereas 'Avatar' and other movies get shocks out of their three-dimensionality, 'Gatsby' is going to be about inviting the audience into this larger-than-life drama, letting them almost be inside the room rather than looking at it through the window. I think it will really work.