Dresses for Eid and weddings

I will start with that kind of dresses for Eid parties, where in some cases we women we are toghether in family, no man there, but that doesn't mean that men won't be present later on at the party :) So those dresses are best to be on family parties , just to feel confortable, but if you wish to use it at some parties kept on different places with  non mahrams guests, then is it preferable that you should put under just a lovely turtle plain top or to use the  or  to take a bolero in tone with your dress or just  to put on top a plain black open 3abaya.  .