This varies with individual preferences. In very warm climates you may spend more time in your air-conditioned cabin to get away from the heat. If you think you are going to be spending a good deal of time resting, reading, sleeping, or if you just want to be alone, you may want to book a larger cabin. On the other hand, if you know that you are only going to use the cabin for changing clothes and sleeping, a smaller cabin would suffice. Outside cabins cost more than inside ones.
Prices also rise as the cabin gets closer to the top deck.
More expensive cabins may have more square footage, a balcony, mini refrigerator, and bathtubs. Cabins at the bow and stern of the ship are sometimes less expensive due to space limitations imposed by the ship's structure. When deciding on a cabin, determine how important the different features are to you. If you fear seasickness, book a cabin that is nearest to midship. The center of the ship generally has less pitch and is more stable.