For me, literally half the reason the Star Wars movies seem so big and so epic is because of John Williams' incredibly awesome musical scores. The music of Star Wars makes every film as listenable to as a symphony concert, with character themes and mood tones set for the sound that are as comfortable as old leather.
With a new soundtrack being written for Episode 3 as we speak, I thought it would be a nice change of pace to focus on this aspect of this movies.
Personally, my favorite Star Wars music can revolve around what's sort of my own "Top 10" greatest hits or so, but there is usually one particular piece or another of John Williams' execellent collection of work that gets triggered in my head any given day when I wake up to my huge Star Wars collection that so dominates my home decore. Right now as I write this, I can hear the new ending-celebration score from Return of the Jedi's special edition play in my head, and I think I could just listen to that for hours inside my mind, or I could even whistle along. It may even prompt me to put on the movie in the background while I work - or at least the soundtrack.
What is your favorite Star Wars music?