We still haven't seen the Stormtroopers running into the Wampas holding room in ESB. Just stills. Also the scenes with Ree Yees and the other alien arguing around R2 in Jedi on the sail barge.

What I'd really love to see are the original workprint versions of the OT. The original versions of SW and ESB are especially interesting because they are put together so differently. In Skywalking they talk about Lucas' version of ESB losing character moments and being really fast. Would love to see his version of trying to make the film work.