here's what i finally decided on, although that decision could change at any minute :)
the next step is to piece everything together, starting with the three layered squares. i'll top-stitch each of those, and then piece each of the 9" squares together. quite the process!
once that's done, i'll start on the animal border. i'm thinking i'm going to use some of the leftover colored fabrics to block out the corners of the quilt, and then applique some of the bigger animals (cut from the Noah's Ark Panel) on top. it'll be a good test of my newly-learned skills.
let me know what you think!