That's the perfect size for kids that age -- big enough to lay on, under, in... but small enough to drag around. My kids are just a bit older and still prefer their quilts about that size.
My MIL did rag quilts a few years ago for christmas and bordered them... she did kind of a really wide binding if I remember right. Sewed 2 strips together and folded them in half then attached them to the edges of the rag quilt -
I wouldn't though - I think your quilts are just right as they are.