A trip to a spa hotel is all about relaxing and unplugging from the real world, so bring clothes that are casual, loose and easy to slip out of. T-shirts and tracksuit pants are good options. Slippers and fluffy bathrobes are customary spa attire, but these are usually supplied by the resort. Planning on going for a dip in the pool or doing a workout? Toss some gym wear, sports shoes and a swimsuit into your suitcase too. If your hotel has a restaurant, see if there's a dress code — you may need to bring a smart outfit to wear to dinner.