I think that a solid pink would look nice! I would cut the sashing strips in 3" widths and sew them to the sides of the blocks. Then sew the blocks together in rows of 3 blocks each. Next, sew a 3" strip to the row across the top and then sew the rows together so you have 4 rows with 3 blocks in each row. Sew another 3" strip to the top on the left and the right sides and then on the top and the bottom. Add another 1 1/2" strip of a contrasting color (white or yellow or lavender) to sides, then top and bottom again. Finally, sew on a border about 7 or 8" wide to sides then top and bottom.
Please post pics when you are done! I would love to see how it turns out!