I love your fabric/color choices so far! What are the colors in print? Find a blender or solid that goes well with one of them, and then see if it works well with all of them.
If you have enough of the 3 fabrics in the block, just use that for the quilt. I think if you alternated the squares/rectangles around the white fabric, you'd have a very striking quilt. Or put a white block between each 6 patch. You could also simply sash around each block with the white fabric and that would look great!