Maul: Athletics, playing a bunch of droids in a capture the flag game or something.
Dooku: Painting / sculpting / orchestra. I see him as the sort to patron the arts.
Palpatine: Dark side artifact collection, largely to gain power. The type to never stop working.
Vader: We see him in some sort of tube without the suit. He might hate the suit and prefer to be in the bacta, just chilling. Maybe he goes on the Star Wars internet equivalent.
Snoke: Wonder about his backstory.
Kylo: The exact kind of person you’d expect to excessively tweet.