STYLETHREAD -- LET'S TALK SHOP!

I bought this Banana Republic dress for a wedding next Saturday. It is an evening wedding, so I think will be quite dressy. I found a black necklace that is choker length, but drops down pretty low in front--very antiquey. The dress is a weird color but with black straps, so I think wearing it similar to the picture on BR with black tights and closed toed shoes would work. Am I on the right track? Would you all do a sweater or wrap over it for warmth? Any help is most appreciated!