Andrew - I'm sorry this is so late, but I wanted to add some feedback as well. My sentiments are very similar to Jen, honestly, and she was so thorough I'm not sure what more I could add to that! So will keep it simple- I was immediately drawn to the hexegons - I just thought it worked well with the layering of your story in addition to the design aesthetic you are going for here. I do think a different typeface would really punch this up, maybe a clean, tall sans serif. I'd also maybe explore the text weaving in and out/hiding behind some of the shapes.
In regards to perfect binding, all of these posts are extremely helpful and I am at a loss as to what I can contribute to this conversation at this point as this is my first time perfect binding as well and there is a wealth of great videos here. I was talking to a friend who had taken the class before who recommended making your book 5.5 x 8.5 inches so that you can just fold letter-sized paper in half without worrying about
trimming it. I can pick her brain a little more with some of the questions posed here.