All cabins come with basic amenities, such as the services of a cabin steward to clean your room and turn down the beds, soap and shampoo in the bathroom, individual climate control, etc. But certain categories of stateroom come with added perks. Suites come with a variety of extras and privileges, everything from priority boarding to in-cabin bar setups. Spa cabins will offer spa-related perks, such as yoga mats in the cabin or a fancy showerhead; concierge-level cabins will give you access to a concierge and niceties like afternoon canapes; and even solo cabins might offer extras, such as the use of an exclusive lounge. How do you want to be pampered on your vacation?
Do you need a balcony? Cruise travelers who spend all their time in the public areas -- sun decks, lounges, restaurants -- or on shore may be perfectly happy with standard-size cabins and no private outdoor space. Those who love to avoid the crowds and lounge quietly on their own verandahs or have private room-service meals outdoors will surely want balconies. Do not forget to take your itinerary into account; on a chilly-weather cruise, you might not be spending too much time outside, so depending on how much space and light you need, a balcony might not be worth the splurge.
Since cruising has become a popular family vacation, more new ships have built "family accommodations" into the actual design. These are often suites, each with a separate room for the kids -- sometimes a small alcove with bunk beds, sometimes an entire adjoining cabin. Families and groups can also take advantage of regular staterooms with third or fourth berths found in pullout sofas or pull-down bunk beds (called Pullmans). If you are going to squeeze your whole troupe into one cabin, make sure the space is big enough to accommodate the lot of you ... and all your belongings.
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.