I like Macy's and JC Penney but I don't know about moisture wicking clothing. Walmart had some plus work out stuff as did my local ShopKo (between a Walmart and Target). It is frustrating trying to find nice plus things but just more incentive to get back in those regular sizes! Good luck!
JC Penney had some pants that had wicking in them, but I really like the Junonia catalog. www.junonia.com
Great stuff, but can be a little pricy. If you shop the clearance area and Juno's closet, you should be fine. Great products... especially the swim suits.