The adventures of Han Solo or Lando Calrissian. Young Qui-Gon and his Master Count Dooku. Mandalorians. Boba Fett, anti hero.
I wouldn't mind seeing all of these. The Qui-Gon and Dooku idea sounds really intriguing, since before his alienation from the Jedi Order and fall to the Dark Side Dooku was one of the great swordsmen of the organization and a Jedi of exceptionally high standing.