I love 2001. I sat down with the DVD (checked out from my local library for free!) and sketched stills I thought were setup in an intriguing way. Everything was drawn with an 05 Micron, black Pentel felt tip, and gray Tombo marker.
A couple of thoughts: I saw that the shape of the monolith was hidden in scenes throughout the movie. Sketch #8 shows how the shape of a background pillar sort of symbolically becomes the monolith watching the meeting of the US scientists. Also in Sketch #23 Old Bowman reaches up towards the top of the frame. The black shape of the letterbox becomes the monolith-that is so clever! It also echoes the other scenes in the movie where an ape or Dr. Floyd touch the monolith.
I also have to mention I cued up Pink Floyd's "Echoes" with the last section of the movie "Jupiter and Beyond the Infinite." It is so damn awesome how the music and the visuals sync up especially with the last appearance of the monolith in front of old Bowman's bed. I totally geek out everytime I do that. :)