i would say some kind of necklace close to your throat - not necessarily a choker if they make you uncomfortable, but something that wouldn't dangle much. if the dress is really decorated (i'm having difficulty picturing it), maybe something really simple, like a silver chain or plain silver choker, or a string of somewhat subdued beads?

(i probably actually have something or other you could borrow, even - a couple of sleek silver chains that could be looped, f'rinst)