I haven't read all the replies and I hope I don't repeat something. Can we see a picture of the quilts?
Suggestions:
Stitch in the ditch
If you have a machine with decorative stitching, you can go over all or some of the seams with the decorative stitch. I did one with a blanket stitch and I really like the way it came out.
A lot of people still tie quilts.
Criss cross the squares or blocks
Use a stencil or two. If I could see the quilts, I'd have a better ideas. Now I'll go back and look to see if you already posted pics. ERRRRR.