I need a dress for christmas!! whats in/out?

i need to buy a semi-formal party dress soon, and before i go shopping i want to know whats in and out? like, are laces and bows out and sequins are in? is it all about over the top glamour or simple elegance? pleeease help... and i want a dress thats around $100 or less, because i need a grad dress too and i would rather spend money on that. holla at me!