The costume isn't suppose to be scary, its the man inside the costume that is the frightening part.
Neither film nor comic representation of the costume really isn't anything other just then a ways of hiding Norman's face and being one of his many (psychologically speaking) masks.
But that picture you posted, that is how i see Gobby, whenever the name Green Goblin comes up, i think that picture (comic book wise) is the style i shoot right towards. Its very classic, but sleek, has some mystery to it, but you also gain an idea of crazy. It works on all levels for me.