A trip to a spa hotel is about relaxing and leaving the world behind, so take clothing that is light, casual and easy to slip into. T-shirts and yoga pants are perfect. Bathrobes and slippers are typical spa attire, but these are usually issued by the hotel. Planning on soaking your body in the hot tub or trying out a yoga class? Squeeze some workout gear, sports shoes and a swimming suit into your suitcase too. If your hotel has an on-site restaurant, check if there's a dress code — you may need to bring a smart outfit to wear to dinner.