This is my one-piece. I fell in love with the pattern and figured that the padding in the cups and the ruffles would hide my chest. However, wearing it on a number of occasions has revealed a few problems.
1. The ruffles only hide my chest if they are sitting a particular way. If the water sweeps them aside, all bets are off. So I end up constantly rearranging the top to prevent inadvertent scar exposure. At some level, I think anyone trying to look down my top probably deserves what they get, but I don't feel like being forced to deal with other people's sensitivities because of a wardrobe malfunction. I have read a suggestion that net bath scrubbies can be used to fill out the cups of swimwear and I may give that a try in order to get the back of the cup to sit tightly against my chest wall.
2. I needed to size down in this to get the right fit across the chest. Unfortunately, because I am fairly tall, this has resulted in the body being a bit short for me so I am often pulling the suit up or down.
Here is my bikini. Now, this is more skin than I have exposed since my 20's but this suit is far more practical than the one-piece. The top completely hides my scars. The gathering and a small amount of padding prevents the fabric from clinging and sticking to skin that is a bit bumpy around the scars. I swim in this very comfortably and don't have to worry about fabric shifting or exposing my chest. The down-side is that it exposes a lot of the rest of my body.
In practice, I tend to wear the bikini in the pool at home or on the beach where everyone else is similarly dressed and I can blend in with the crowd. If I am invited to someone's home where swimming or a spa is planned, I will take the one-piece, especially if there are people there who I don't know well or if there are men present. I have noticed that rash-suits are starting to become more common and that is certainly a practical option both in terms of coverage and sun-protection. I will look into that possibility next summer, but as the warm days draw to an end I will try and get as much wear as I can from the choices I already have. Ultimately, it is about balancing comfort and exposure and doing what feels right for you.
Twisting By The Pool by Dire Straits