For the ending of the original trilogy, I think the original music works well. As the end of a six film saga, however, I agree that victory celebration is more fitting, as well as the images of the celebrating galaxy, however nonsensical they actually are.

There's yet another angle to look at this from, however. If episodes 7, 8, and 9 attempt to conclude the entire saga, I believe that the original Yub Nub song could work remarkably well, as it gives the message that the victory of the Rebels was only a local victory, and as such warranted only a local celebration. The audience would look to the final trilogy to complete the story, whatever it turns out to be, and the end of episode 9 would conclude on a victory celebration on a galactic scale, and one that was truly warranted.

Edit: Tyrphanax, you beat me to it.