By the way, I have a thread on the TFN forums where I analyze lots of the costume concepts and other character designs done for the OT. Many of the drawings there are by Ralph McQuarrie, but some are by other artists, such as John Mollo and Nilo Rodis-Jamero.

Fair warning: the thread is intensely image-heavy. Do not go there if you have dial-up (or are still living in a cave in 1992).

Also, there may be some potential Episode VII spoilers--but likely nothing you haven't encountered already.