I like Linda the Bra Lady. http://www.lindasonline.com I've bought bikini sets by Freya and by Fantasie. Both seem to be of comparable, good quality. I know that Fantasie sizing can be a bit different, but the suit fit true to size as the Fantasie bras that I was purchasing at the time--sorry, it's been a couple of years since I bought Fantasie products and I can't remember how, exactly, they differed in fit from my "regular" bras and such.
The only fit/style issue I'd caution you about is to get enough coverage for the activities you want to undertake. A lot of the bikini tops are balconette-style and that doesn't give a lot of insurance against popping out over the top if you are bouncing around. I was just so happy to get fitting bikini tops that weren't matronly, that I bought two balconette style tops and I wish I'd chosen a bit more coverage.