To be fair, because this last contest was so close, I'll discuss the ideas posted in this thread with Starscape and we'll decide together.
Thanks, but I should warn you that when I've set these challenges in the past I generally haven't inspired too many entrants.
I'm warming to the "traditional materials" idea, even though it's not playing to my strengths. I suppose it doesn't have to be limited to free-hand work, but also stenciling, graphic and technical drawing?
I had a couple of ideas I might have used had the vote gone my way:
1) Myths and Lengends - interpreting myths and legends of Earth in terms of the Trek universe (e.g. like in TOS were the Greek gods were visiting aliens) or show the myths and legends of the Trek universe (e.g. a space going "Marie Celeste").
2) Picture Postcards from around the Star Trek universe.
I'm not sure how well either of these ideas would hold up whilst keeping the "traditional media" condition, though.