The dominant colour that I see in this is blue ...
I always had trouble staying in that darn ditch - I found a lot more success using some of the decorative stitches. If your machine has a couple of different decorative stitches, you could alternate those - just sew those down the seamlines instead of stitching in the ditch.
Depending on the size each square you have, and the batting you use, you might be able to do every other row.
Nice job on scattering the colours throughout the quilt - you got nice movement. Way to go!