Over night bags seem like the easiest to pack, yet you face the daunting task of picking just ONE outfit, ONE set of your fashionable pajamas, ONE look for your make up, and just ONE bag to carry it all in. 

So here is what I would do:

Wear the most appropriate outfit for the occasion that evening.  Then bring along your favorite set of pajamas, and the most appropriate outfit for the next day.  Don't forget to roll your clothes.  That's the most important part.  Bring along a small bag carrying only the items you need for tomorrow's make up, appropriate toiletries like your tooth brush, toothpaste, make up remover, perfume, etc.  Fit that bag inside your larger one carrying your clothes.  Add in your chargers for your technology and voila! You have the necessary items for your overnight stay.

xxoo,
Claire.