John William's score and Ralph McQuarrie's concept art. It's difficult to capture the kind of exotic epic that can be imagined by simply listening to that music and looking at those images. You can truly feel what the young George Lucas was aiming for. I don't know why, but somehow the feelings I get from those two elements feel purer and even better than even my experience of the film(s).
Does anyone agree? Try it. Just put the films out of your head, play a copy of the soundtrack (I'm sure you've all got one) and imagine your own stories for the characters Ralph has rendered or just soak up the atmosphere. Leia's theme is particularly good for this.
What does everyone else think?