Almost any block can be used, and navy blue and cream quilts are quite striking. I just made a Sister's Choice (also known as farmer's daughter) quilt for our family reunion raffle quilt and it was beautiful in a variety of medium to navy blues with white. An Irish chain would be traditional and striking in blue and white, as well as double wedding ring I would suggest Quilterscache.com where they not only show the blocks, but they show the blocks and some completed quilts in color. I'm sure whatever you make will be fine with your son and new DIL.