Ah, the Binary Sunset alternate track . . . gosh I love that cue. I first heard it in the game Jedi Outcast (it occurs in part in the second level) and I always wondered where it was from, because it sounded Star Wars-y but I didn't recognise it. Once I got my complete soundtrack cd's I finally discovered what it was! I've watched that part of the movie with my cd player doing the alternate track--it matches up perfectly timewise, but the feel of it is so different it's amazing to think what it would have been, if Lucas hadn't asked Williams to write something different instead.

I like the alternate Sail Barge cue as well, also having heard it first in Jedi Outcast. It doesn't re-use the older themes the way the final version does, though Jabba's theme does come in (possibly when Leia is strangling him?). I think the reason they didn't use that was because they kept changing the edit of the whole sail barge sequence, according to Ben Burtt on the commentary, so the music had to be completely redone.

I have that Skywalker Symphony cd as well--it's interesting to hear the various concert arrangements of things that weren't recorded in full for the films. I think the group was only put together for the one recording, wasn't it?