I think I'd pick Guillermo Del Toro as my choice for a few reasons
1.A proven track record of successfully adapting someone else's original world-- With Mike Mignola
2.Showing a fantastical world while still driving solid narrative-- Pan's Labyrinth
3.Working within the context of otherworldly highly stylized non-human characters (several different films)
4.The capacity to keep the fun aspect of a film that doesn't take itself too seriously without overtly winking at the audience (first hellboy).
I think he is a better visual director then a master storyteller, but he already has the rich lore to pull from, and the Star Wars universe, while having a lot to it, does not need complex moral fables and ethos,
I don't know why I didn't think of him, he is an awesome film maker!