Nike Athena WIP

Done on an 18"x12" (45x30CM) sheet of medium weight sketch paper (image has been cropped). Unfortunately this piece is a little too big for my scanner, that's why the image quality and lighting isn't that great.

Anyway I thought that I'd at least post up what I have finished now since this will be one of the largest pieces that I've ever done in four years. With my leave date for the Navy being mid-September, I'm a little leery that I'll have this piece finished on time. It already took me 3 days to draw the line art alone. It's so awkward for me to be using such a large canvas space since I generally don't use any paper larger than 8.5"x12" and for good reason too. Right now I've run into a bit of "artist's block" on this piece, I can't figure out exactly what I want to do with the background on this one since I have such a large sheet of paper and tons of foreground space by Athena's feet.

Any useful suggestions on what I could do for a background would be helpful.