I feel you pain. I asked a very similar questions last year for DD2. What has worked for us is to use tankinis (one peices have never worked for us, but I've heard that Speedo suits are slimmer) and usually buy tops and bottoms separately. We had a garnet hill suit last year that held up pretty well and a suit from Tea Collection that was cute, but didn't hold up as well. I was also really suprised that the suit MIL bought at Justice which was not sized separately fit really well. It was a size smaller than her usually size, but it covered everything and didn't gap. Also held up really well. They start at a size 5 so probably not an option for this year, but wanted to throw it out there for others that might be in a similar boat.
Margaret
DD1- 2/14/05
DD2- 9/24/07