Spa hotels are all about relaxing and logging off from the real world, so pack clothing that is casual, light and easy to slip into. Sweatshirts and tracksuit pants are perfect. Slippers and fluffy bathrobes are typical spa attire, however these are usually supplied by the hotel. Plan on going for a swim or trying out a yoga class? Toss some workout gear, sports shoes and your bathing suit in your bag too. If your hotel has a restaurant on-site, see if there's any kind of dress code — you may need to bring a chic outfit to wear for dinner.