I'm reading this novel during my lunch break. Love it! Love his historical novels in general! Off the top of my head, I am always impressed with Peck's gift for description and detail. I think an easy activity is to draw a scene from the novel.
I also think maybe drawing the characters as they look in the opening chapters and again in the new duds Mom buys to wear to Chicago. Kind of a makeover type activity!
Tell a scene from the point of view of another character would be interesting too. It could be a journal entry or a letter.
Making a scrapbook project of things the characters collect from their trip would be stimulated.
I haven't finished the novel, but I really think it's a wonderful read!