Dress up in fun costumes for the night and make sure to get good spots for the fireworks. Other than that go on the rides you might not have gotten a chance to as much because of long lines and enjoy the photo ops.
The only thing I can recommend about these parties are the parade and the fireworks show. Besides that, not much else there to do. Of course, dressing up is fun, but there is only so much fun you can generate with that.. and they don't even give you candy for your efforts.