I love mixing my backgrounds. I think it makes the quilt more deminsional. If you use white and creames togeather just make sure you test the placement of the pieces before you sew them. When you are at a quilt show , usally the quilts with the mixed backgrounds are the one that people are standing in front of and looking at longer. It draws the eye and gives it interest, where plain backgrounds are good but does not always give you that little someting extra.