Have you tried laying them out edge to edge? Then stand back and look for the secondary designs to jump out. (I see a circular shape of diamonds form, with a four-patch white muslin square in the middle (great for quilting), when 4 blocks are set together. Hard to describe.
The problems seem to be in the triangular piece that fits between each pair of pants. When you press them, try easing that fullness into a dart. Then if you sew in that dart from the back, it might flatten the block. When everything is quilted those occasion extra seams will hardly be noticed.
OR, again sewing blocks edge to edge, match up the longest, fullest seams and pray that the resulting bumps and bubbles will quilt down flat.
Absolutely Love the little blue pants with the yellow and red stripes matched at the center "back" seam. Can't you just see a little diapered bottom crawling or toddling around in them?