I love rectangles! And heartily endorse the idea of the “brickwork” patterns that LAF2019, Tartan, and others described.
Definitely, making one quilt in checks and the other in florals and solids like you mentioned would work.
A few more ideas to play with:
-- Make one quilt as scrappy as possible, and use the same fabrics in a very ordered layout on the other quilt.
-- Maybe use prints you have the most of (checks and solid blue, it sounds like) to create a distinct pattern for each quilt that draws the eye, and mix in the other fabrics as needed. The main pattern could be horizontal, vertical, stair-step, or even (roughly) circular to expand out from the center.
-- Cut the blue solid rectangles into squares and use them to separate/break rows or columns of bricks.
-- Select one of the prints and stitch them all end-to-end to create a one-print "solid" fabric that goes between rows/columns of mixed bricks.
Hope this is helpful. We'll want to see photos of what you come up with!