A very experienced weaver on this topic is Laura Fry. Laura has produced "Magic in the Water" and teaches workshops on wet-finishing cloth. I like how Laura has not only taught many weavers about the importance and techniques of wet finishing, but also been able to make this a part of her business.
Here are three samples of Shetland wool blankets. From left to right, they are unwashed, handwashed and machine washed.
Detailed samples show the unwashed sample as very loose and gauzy. Fabrics right off the loom are also stiff and not very soft to the touch, and they don't drape at all.
And the final sample I tossed into the washing machine with the laundry. It felted quite nicely, which would be great for a jacket or vest. However, for a blanket it's just a bit too thick. As well, the width and length were reduced.