It's all about being comfy and relaxed when you're at a spa hotel, so loose-fitting, casual clothing is generally encouraged. While you'll likely spend much of your time wearing toweling slippers and a robe, these are usually waiting for guests when they check in. If you'd like to take advantage of the fitness facilities, pack your sportswear. Hoping to kick back and relax in the swimming pool or hot tub? Make sure you toss a swimsuit in your bag. In addition to toiletries and other personal effects, bring a change of clothes with you too. It's always nice to have a fresh outfit to slip into after a treatment.