My own personal choices for spinoff films would be, in descending order:
1. A Fugitive Jedi "chase" film where a survivor of the Great Purge flees Darth Vader and Imperial troopers.
I still think something like this would be perfect for the basis of the oft-rumored live action TV series. A Jedi goes on the run and has wacky adventures across the Galaxy Far, Far Away while evading capture.