I found a comic creation tool recently called Storyboard That! It gives you three panels and tons of options for characters, backgrounds, and more. Even better, you can change the colors of background elements, and the clothing, hair and all coloring on the characters.
They give more room than most for text. The boxes are a little large for the panels, but I couldn't quite figure out how to adjust the speech balloons.
Marion and Robin are huge readers.