The ONLY thing I would change in RotJ (refering to the undestroyed, pre 2004 version, of course) is to have Han and Leia's roles in the final battle be reversed:
Han gets shot in the shoulder, while Leia leads the final assult on the shield generator. it would affirm that she is indeed a skywalker:
Her Brother destroyed the first death star, whilst she ensures the destruction of the second.
oh yeah, I wouls also add a big "THE END" to the ending credits before "Directed by Richard Marquaand" appears.