Plymouth Encore and Lion Woolease are acrylic/wool blends that are washable and fairly soft, as well as inexpensive. However, I note that the Boise is a dk weight so they may be a little thick. James Brett marble is a heavier dk, acrylic and semi striping. Look also at knitpicks.com for their dk weight, I think there's a superwash in them.
sue- knitting heretic