My original thinking was to work up a final version in pen-and-ink with a tonal wash. To that end, I inked what was essentially the same base drawing (without shading) that you see above. The result was such a disappointment that I'm not going to post it. Part of the problem is that I drew it too small to get a real handle on the facial expressions. Also, the characters, who are supposed to about twelve years old, looked too young. Today I've been redrawing the same picture at a larger scale while aging up features slightly.
You will notice that I haven't done any inking or shading at this point. As I was drawing this I started thinking of other possible ways of completing the image. I have Adobe Creative Suite 5.5. I have the day off from my day job tomorrow. Maybe I'll see if I can work this into a strong image in the forgiving layers of Photoshop.