My son's absolute favorite quilt was the one my mother made him almost entirely of double knit fabrics from the 60's and 70's. She threw in some flannels for good measure.
We used to shy away from using it for quilts but I noticed my guild's 2012 community service project is laps quilts for hopsice, veterans, and babies, and one of the fabrics they list that you could use is knits. So, sew away!