Spending time at a spa hotel is about relaxing and escaping the real world, so pack clothing that is casual, light and easy to slip out of. Track pants and T-shirts are perfect. Slippers and robes are traditional spa attire, but these are usually issued by the resort. Planning on going for a dip in the pool or trying out a yoga class? Toss some gym wear, sports shoes and your bathing suit in your bag as well. If your hotel has an on-site restaurant, see if there's a dress code — you may need to bring a chic outfit to wear to dinner.