Also, I know this might not be helpful for those over a size 24, but if you are 20-22 or 24 and small chested (as fat as I get my boobies stay a B (now C) cup), there is a control top from the Gap that is much more comfortable than any plus size or maternity spanx tops, it's long and really helps smooth out my B. Combined with maternity full panel pants, I feel supported and round, not hanging. You can see it here. It's very stretchy but I imagine if you have a D+ cup size it might hurt the boobies.
https://www.gap.com/browse/product.do?cid=7275&vid=1&pid=761563