How about a Native American? Given the unique and unusual relationship that American Indians have with the Federal government as citizens of various derivations of quasi-separate nations, a Native could provide a valuable perspective to the SCOTUS’ ruminations.
I have no idea if there is an able Native justice out there, but since there will be an element of “just because” to this selection then you might as well go with a Local.
Also, I welcome the inevitable Conservatron hyperventilating and projectile vomit of fnords over whoever Obama selects. Please let them fool themselves into believing that a proxy fight over whatever wedge issues no one cares about anymore is their way out of the wilderness. This is just proof positive that there is no need to take them seriously for now.