Some men can find women with tattoos on the hip sensual, since it is an attribute zone of them and a tattoo there can make it notice more. Any ideas:
Lunar Phases: You can relate each lunar phase to a different cycle of your life.
Diamonds: Brightness, power, strength, resurgence. You can use a diamond on each side of your hip.
Galactic motives: Moons, planets, cosmic dust, comets, galaxies. If you like the subject, I look for one that you like for your hip.