JC Penney online (www.jcp.com) actually has some cute tankini styles - and there is a good selection out in their stores right now too, if you can wear regular sizes.
I just bought a really cute plum one with great bust support and a short skirt. The material is actually rather substantial, which is nice for support and for help with loose skin. It is this one (if you don't like the ruffle bottom, they have a different skirt option):
http://tinyurl.com/7jnccd6
There are several choices with board shorts too. I think I'm going to get one of them closer to my vacation in June since I'll be doing more active stuff then.