Hands down, DeSoto makes the best tri wear I've worn. Their seams never seem to chafe, and their built-in bras are really supportive. Best customer service ever -- when I had some fit issues with a wetsuit the owner of the store personally emailed me to get the issue resolved.
PI stuff is also really good, but I found it to fit better if you have no curves. I have wide hips and broad shoulders and could never find a fit that I liked.
Nothing to add except that I'm looking for a 1-piece tri suit too. I had a 2-piece last time and the shorts caused drag and the top rode up. It drove me nuts! Let me know what you find out!