I just noticed that the line "You and you and nothing put you, miles and piles of you" appears in both I Can Do Better Than That and in See, I'm Smiling. I thought it was interesting that Cathy uses it first (chronologically) in I Can Do Better Than That to tell Jamie that she loves him as his and he doesn't need to change....yet when he does change, she uses it against him later in See, I'm Smiling. The same thing she wanted in the beginning later became the thing she resented. I just found it interesting, and quite consistant with Cathy's character.
Another subtle move by Jason Robert Brown to make L5Y one of the most lyrically beautiful and complex stories I know.