I wouldn't underestimate the attractiveness of a one-piece. I feel that a bikini often looks odd. There's too much skin so I prefer a flattering one-piece that accentuates natural curves without being over-whelmingly bare. In a way too much skin is some what blinding. It's nice to have a piece that covers you up and leaves the rest to one's imagination. That's more sexy in my opinion.
By the way I am referring to one-pieces that involve a lot of back showing and shaping around the breasts and waist :) Not a grandma suit.