A quilt that I have on my bucket list is Illuminate featuring Red Rooster fabrics. It has all sizes of circles. I am sure the pattern has templates in it that are sized to what the pattern designer wanted the pattern to look like. The thing about circles is that anything round can be your template. The fun part is deciding how to stabilize them if they are larger ones.
http://www.love-to-sew.com/illuminate-quilt/
ps...just wanted to add.... I might better buy a fabric kit soon, because the fabrics for this quilt are so unique that it might not look that good with a different collection of fabrics. The pattern itself is free as a downloadable PDF.