Speedos and Jammers for you guys. There are also 3 swim shirts at the bottom that are tight, so they don't create much drag I promise. I have tried the shirts myself and was shocked. Swimsuits are made of a higher quality material, so need to worry there, I hate cheap swimsuits.
There is a mix of two-piece and one-piece swimsuits for you women. I am a guy so to be honest this isn't my specialty, but these are all made of thicker materials, to hold everything in place, while offering the best mobility, and drag reduction. Also, some swim caps at the end, should help.