I would have done a few things in the first film differently.

I would have had Luke's life on Tattooine fleshed out a bit more (in good ways, like the deleted scenes)

I would have had a scene somewhere in the film of the Emperor, hidden in the shadows entirely, but just enough of a presence.

I would have fleshed out a bit of an animosity between Tarkin and Vader, sort of like the original conceptions of Vader and Jejerrod from ROTJ.

I would have had Leia only guess that they were let go, and have those fears confirmed once they reached Yavin.

But, then again, this is all speculation.