Taking a trip to a spa hotel is about relaxing and escaping the real world, so pack clothes that are light, comfortable and easy to slip into. Tracksuit pants and T-shirts are perfect. Slippers and fluffy bathrobes are typical spa attire, but these are usually issued by the resort. Plan on going for a swim or loosening up with a yoga class or two? Squeeze some sports gear and your bathing suit into your suitcase as well. If your hotel has a restaurant on-site, see if a dress code applies — you may need to take a smart outfit to wear to dinner.