Two in one dresses have had something of a resurgence of late, and while a dress and top combined may not be any more practical than separates, some are worth a look. This Dristi Dress by Theory is a cute, 60s look version that's simple and chic.
Combining a wool vest top with a plain black mini, the dress works the sixties block colour look well in subtle grey and black. The skirt has a high waist and an a-line cut, combining with the fitted vest top to provide a great retro silhouette.
It's available from Shopbop online for $297.