I think if you using a dark colored sashing between the scrap blocks, it will help bring the whole quilt together. I'm working on two right now....and (after looking at many people's quilts here), decided to try using bold colors--one with red and one with a bright blue...It really does make a difference.
The soft, muted colors (for sashing) don't give the definition to the blocks as well as the brighter colors. I've got SO MANY scraps that I'm going crazy trying to use them up--or at least under control.