Penny, Broadcloth can be used in quilts. It is usually solid colors. Most quilters prefer 100% cotton but many use blends. It is all a matter of personal taste and what you can afford. I live within easy driving distance of both AMish and Mennonite communities. As they are the ones that have truly kept quilting alive they know what they are doing. I have often noted that many of their quilts and even their clothing is often made from blends. Knowing that they often have to make every stitch of clothing their families make I can not begrudge them the little luxory of fabrics that don't wrinkle as much. Most of us will admit to using whatever fabric provided the color or look we were seeking for our quilts.
Have fun and don't worry about the quilt police.