Spa hotels are about relaxing and breaking free from the real world, so take clothes that are light, comfortable and easy to slip out of. Tracksuit pants and sweatshirts are great options. Toweling slippers and robes are classic spa attire, but these are usually provided by the resort. Plan on going for a dip in the pool or doing a few exercise classes? Toss some workout gear, trainers and your bathing suit into your suitcase too. If your hotel has a restaurant on-site, find out if there's any kind of dress code — you may need to take a chic outfit to wear for dinner.