An Empire Strikes Back suggestion to throw out there. I think some of the 2004 dialogue for the Vader-Emperor conversation could possibly be rearranged to improve the scene a bit:

VADER: What is thy bidding, my master?

EMPEROR: There is a great disturbance in the Force.

VADER: I have felt it.

EMPEROR: Luke Skywalker.

VADER: Yes, my master.

EMPEROR: The Force is strong with him. The son of Skywalker must not become a Jedi.

VADER: He’s just a boy. Obi-Wan can no longer help him.

EMPEROR: He destroyed the Death Star. He could destroy us.

VADER: If he could be turned, he would become a powerful ally.

EMPEROR: Yes…yes…he would be a great Sith. Can it be done?

VADER: He will join us or die, master.

Three points to justify it: first, it's never made sense to me that Vader or Palpatine would consider Luke a "new" enemy several years after he saved Leia and destroyed the Death Star. Second, the line about Luke destroying the Death Star makes it a bit more substantive of a conversation by having Palpatine provide an actual counter-argument to Vader's protest. Third, I like the idea of working the word "Sith" into ESB and/or ROTJ once or twice.