I just buy what I like. I'm also finding out that while I like to use patterns for some projects, I also like to pluck fabrics from my stash and let my creative self go. (I'll never win awards for my work, but I do have fun.)
My "grands" also get to pick from my stash and at clearance prices, I don't feel at all bad if something they do goes awry.
Sometimes I buy their clearance fabrics to use as pieced backings, as I like the back of my quilts to have some personality, too. I especially like to do that for baby/toddler quilts so that the quilt can 'grow up' with the child.