Diurnal Monochrome

I suddenly got a lot of unplanned free time, so I thought it would be well spent on ponies. Thus I give you, Princess Celestia in all her monochromatic glory!
She turned out a LOT more pink than expected. Well, that's what happens when you draw half asleep. Or it's because it's hard to find high res screen-shots of Her Royal Highness.

Anyway, she was fun to do. I'm thinking about doing Nightmare Moon next, but I'm not sure.
Do YOU have any suggestion as to which pony should be monochromized? Feel free to share