Not that I think people are looking at my bum, but.....?

I have a pair of white capri sweats I wear to the gym and casually. I want to know if I should wear full bikini panties with the obvious line and bum bump, or a thong which is also visable, or panty-less (a la britney). I do have an ample bottom but no visable cellulite. Whatchall think?