I wonder if you could just re-do the middle 4 patch blocks. Maybe use solids or tone on tones with a bit more contrast. I know your nieces will love what you make them. But you also need to be happy with what you make.
I once took a whole quilt apart (100's of triangles). I hated it when it was finished. Little by little, I'm still using up those triangles in other things.
Whatever you decide, will not be right or wrong. Just try to be happy with it. I LOVE the Pattern and the Outer edges of the blocks. I also love the sashing color. Will look forward to seeing what you decide to do.