When I was building my cinema room, even before the projector was put up I had my speakers installed in the ceiling. One of the movies would be in my DVD player quietly playing in the background as I calculated and hammered away.
Hard to say for my favorite song cause they all have a time and place. I like the cantina music as it played while Han and greedo were talking, but my fav would be the end song from ANH and transition to to trailing credits score (which the concept of ending credits was a first in Hollywood history).
For me it was the best movie and come to the end of it I was all pumped up. Seeing it for the first time, you knew it was over and didn't want it to end. After Chewies roar the end credits flashed up. Awsome moment!