Reply to Love to Sew (instead of quoting the whole message):
Great ideas! Thanks! And yes, I agree with all you say. I've already rearranged the section that shows the three purples together, in a 3-sided box. I did try to distribute the purple in each row as you suggested, as well as the red and white stripe. I also have to be conscious of the two red and white patterned fabrics and make sure they are as evenly distributed as I can get.
The reason I have no design wall is that I have no wall -- or not an expanse of wall large enough. I do have flannel that I bought to make a design wall, just no good place to hang it. But I may try again over closet doors, just for this quilt.
Thanks for your response and ideas!