If you tend to get seasick, cabin location is really important. It is a question of engineering, really. The lower and more central you are in a ship, the less roll and sway you will feel. Even if you choose a balconied stateroom, choose the lowest level and the most midship one you can find. The higher decks and cabins at the very front (forward) or back (aft) of the ship will rock and roll the most.
In order to set the pricing many cruise lines will divide each cabin type into sub categories. For example a balcony cabin may be divided into sub categories such as B1, B2, B3, B4. In most cases the cabin size and features in a sub category is the exactly the same. The only difference is usually the location of the cabin on the ship. Please look for the notes on the category descriptions to determine if there is a difference in size or features between the subcategories.
Cabins are priced based on location on the ship. Typically cabins on lower decks are less expensive. Typically cabins midship (in the middle part of a deck) cost higher. Balcony and Suite cabins on the very aft of the ship can also be more expensive than other cabins.
Other pitfalls include service areas adjacent to or above your stateroom; show lounges or bars adjacent to, above or below your stateroom; and self-service launderettes across from your cabin. Other cabins that can be problematic are those that are situated low and at the back (because of their proximity to engine noise, vibration and anchor) or low and forward (because of bow thrusters).