It depends on a lot of factors. Like the dress, how many people will be there, and if who will style. If you know a lot of people will be there go for the updo, because a lot of dancing combined with a lot of others peoples body heat will make you sweat and you will feel disgusting by the end of the night. If you plan on doing it yourself, go for a style that fits your skill level and make sure to do test runs, if you are getting a stylist schedule it months in advance. That way you get your favorite stylist and you will not be the only girl who plans to go out to get her hair done so best to schedule it early.