Plymouth Encore comes in a DK weight and it machine washes beautifully, but I should note that I find it itchy.
I knit a sweater with James C Brett Marble and it comes in DK. It's soft and machine washable and the colors are very pretty!
I'm now knitting a sweater in Berroco Vintage and it seems much softer even though it's actually more wool. It also machine washes well, but it's worsted weight.