Love Bree's ideas!

Yep some Brighter Green and Yellow and Orange in the Sashings and Borders and then bind in the Blue.. or add some appliqued Triangles or Rectangles in those colors overlapping the Circles.... just suggestions...

My first impression was red sashing with yellow cornerstones. Usually when I have that kind of thought jump out at me it is a great starting point. I would audition them and then start playing with the colors - maybe the red would morph into more of an orange ?? and the yellow into more of a brown??? a tone on tone?? But, first, I would move the blocks around so the blues are a bit more evenly distributed (upper right has several very similar ones). Please let us see what you end up with. I'm sure the right sashing will make it very balanced and set off the circles. Another thought - if it is a modern guild, maybe think outside the traditional box. Rather than basic sashing, why not do 2 rows but of slightly different widths. Example, between row 1 & 2 have a 2" color A and then a 1" color B sash. Between 2 & 3 you could do the same or reverse them. Same with 3 & 4. Same idea with the vertical stripes, but I would definitely do them opposite - 2" color A and 1" color B and then 1"color B and 2"color A. I would then frame border it with color B and end with a wider border color A. This would give it a new spin.

Bree123 has my vote. Very creative.

You need to add some interest in the form of patterns and prints.

applique something in center of each circle or coming out through it . such as leaves or flowers.

I had a similar problem with a quilt I have put away for awhile--before I chop into 1000 pieces. I had some of the colored bead-things that come in packages at Wal-Mart. In trying them out, it improved the look of the quilt a lot. You can choose what colors you want, as the package has every color imaginable.
Our WM. has them I the fabric dept. and they are in plastic containers -hanging Will be interested to know if this helps.
I glued them on with Elmer' s School Clue, as I had surgery on my arm after breaking it, and the 3 nerves on to of the Humros Bone do something that causes a lot of pain so I just machine quilt now until this leaves if it does. You might want to try the glue.
Mariah

Bree123. Your last idea and picture is more to my liking.

I was just in Pinterest and typed in 'quilts with circles'. WOW!!!! One in particular that I liked is making these circles into flowers, stems and leaves. Lots and lots of ideas - may want to make one myself. Good luck.

I was thinking the same as Paper Princess. Seems like it would make for an interesting design.