I know you've said before you have a larger cup size so I'd strongly urge you to buy an underwired one by your bra size. I've heard amazing things about Freya suits (I haven't tried their suits yet but I have some of their bras so I can highly recommend them). Personally, I prefer two pieces because it's too hard to get a one piece that fits both my top/bottom correctly.
At the moment I own a Fantasie one piece:
That is very supportive and looks great. However, I have found that it doesn't fit my long torso very well and I get the impression it's made for someone with a much shorter torso than me. So next time I would definitely buy a two piece. But the support is great and I use it to go swimming/water aerobics, no problem. I have to say it's extremely flattering too.
I don't know if your breasts are wider+flatter or more long and narrow. Freya bras/suits work better for narrow breasts and Panache work better for wider breasts (I haven't tried their suits but I know some love them, they don't work for my breast type so I doubt I'll have bother).
I've worn bathing suits that don't go buy my bras size my whole life and now I just buy underwired ones by my bra size, there's absolutely NO COMPARISON when it comes to support/appearance. I'll never buy another one that doesn't go by my bra size again.
Good luck and have fun!