JS Collections
JS Collections is done by the same company that does JS Boutique. While there is some overlap between the 2 brands, JS Collections tends to be just a bit higher end.
While I see a few JS Collections Plus Size styles pop up a bit here and there every once in a while Nordstrom has the best selection of JS Collections Plus Size and carries it on a consistent basis.
Next Plus Size Designer -> Juicy Couture Plus Size

