I love the look of a different fabric peeking out from under a knit sweater. I've seen one that I particularly like at Zara as well (see below). The chiffon peaking out from the knit material is just so chic! Although you can't tell in the picture, in person, this sweater has a faint hint of shimmer to it -- so cute.
Maybe we could call them peek-a-boo sweaters. What do you think of them?