You can leave that enormous suitcase for another time because you won't need to bring very much to the hotel. You'll likely spend quite a lot of time dressed in toweling slippers and a robe, but typically these are provided to guests by the resort. If you'd like to go for a splash in the pool or engage in some relaxing aquatic activities, pack your bathing suit and extra clothes. Casual, non-restrictive garments are a good choice. Considering using the fitness facilities? Bring some workout attire and quality trainers. Oh, and don't forget to take your toiletries!