A trip to a spa hotel is about relaxing and escaping the real world, so take clothing that is comfy, light and easy to slip in and out of. T-shirts and yoga pants are great options. Slippers and robes are classic spa attire, but these are usually provided by the hotel. Planning on soaking your body in the hot tub or doing a couple of fitness classes? Squeeze some workout gear, trainers and a swimsuit in your suitcase as well. If your hotel has an on-site restaurant, find out if there's a dress code — you may need to bring a stylish outfit to wear for dinner.