It Don't Matter
It doesn't matter one little bit what you wear. Even if you have frog skin Japanese riding boots, you get the dreaded SSSS on your Boarding Pass in the US and off comes the shoes. Always amazes me. The SSSS are supposed to be computer generated, yet it is usually the single (travelling that is) white anglo saxon that appears to get picked.
I wear a medium size watch and on a my last two visits to the US this year, I've played a little game going thru the various securities. As I walk thru with the watch on, I allow my arm to swing slightly out from my side. Sure enough, off she goes. Next time I walk thru with my arm across my midriff. No alarm. Try it some time.