First Choice - Space Gray with Coral interior. The darker gray shows off the lines well and contrasts with trim pieces without being as problematic as black in terms of swirl marks, spider webbing, and the other hassles associated with what is other wise the prettiest color. Space Gray is also dark enough for the metallic effect to show up nicely. The Coral interior contrasts nicely without being so light as to reveal all the dirt, and it ties the inside to the outside via the taillights. (It is noticeably lighter in person than in the BMW generated pics in my sig.]
Second Choice - Titanium Silver with black interior. Silver hides dirt and water spots really well, making it very low-maintenance. The black interior would contrast nicely and provide a simple two-colors inside and out design theme inside and out.