First of all WOW!!! Triplets :D:D:D AND they sew with you too!!! :D:D:D
I think it may depend on the fabrics... If the bigger areas are lighter colored fabrics it would be fun to quilt something in these areas that are meaningful to them. If it is similar to the quilt pictured above, an all over design would be very pretty too, something of interest or meaning to them.
I can't wait to see their quilts :D:D:D