Taking a trip to a spa hotel is about relaxing and logging off from the real world, so take clothes that are casual, loose-fitting and easy to slip out of. Sweatshirts and tracksuit pants are a good choice. Slippers and plush bathrobes are standard spa attire, however these are usually supplied by the resort. Thinking of splashing around in the swimming pool or doing a workout? Throw some sports gear and your bathing suit into your suitcase too. If your hotel has an on-site restaurant, check if there's a dress code — you may need to take something fancy to wear for dinner.