Thanks, everyone, for so much great information! I had never thought of using variegated in the bobbin too, or that I might want the thread to be brighter to show it off. I need to research some of these other brands of variegated thread too.
I am wondering about shininess in the thread now. King Tut is all cotton, which I normally like, but I am wondering if the polyester variegated threads have more shine and sparkle.