Hi sion - I'm hoping some of the other ladies can be of assistance to you. Not only have I used scraps but have also purchased pre-cut sixteenths to get as much variety as I could. I have only done a few blocks so far but like many of the other ladies, have used different colours for each block. I have some batiks with varied colour ranges in each piece and have still gone searching for more. It has become a bit of a compulsion to gather far more fabric than I will need for this project.
Lisa (lisamortell) used a specific focus fabric throughout her quilt - perhaps you could PM her.