This one from Anthropologie is also a great choice. The sweater material isn't super stretchy and clinging. The wrap around ruffles flatter the feminine shape and provide a little tummy camouflage without creating bulk. The cap sleeve won't get in the way of layering long sleeve under or over the dress. And the skirt looks full enough to accommodate the hips other sweater dresses forget about.
This Whirling Ruffles Sweater Dress is a little pricey at $188, but it won't be going out of style any time soon so consider it an investment if you fall in love.