In this age of mega-ships, cabins now come in all shapes and sizes. In addition to the typical boxy inside and outside cabins, you can find expansive suites, duplexes and lofts. Balconies also range in size from small affairs barely able to squeeze in two chairs and a drinks table to huge wraparound decks with outdoor dining tables and hot tubs.
Very few ships actually have cabins dedicated to solo travelers. These will have sleeping space for one and can be quite small. The studio cabins on select Norwegian ships are the most famous example of this: The 100-square-foot staterooms each contain a full-size bed, nifty lighting effects and a large round window that looks out into the corridor. If you are a solo traveler, you will want to price out the cost of a solo cabin (usually somewhat higher than the double-occupancy rate of a similarly sized stateroom) compared to the cost of paying the single supplement (an extra fee tacked on if there are not two people in a cabin; the price can come out to as much as double the regular rate) for a standard cabin. And book early, as solo cabins sell out quickly.
If scenery is important to you, take a good look at your cruise itinerary before selecting your cabin, specifically if you are choosing an outside or balcony. On a roundtrip Caribbean cruise or a transatlantic crossing, for example, the side of the ship you are on does not really matter. If, on the other hand, you are doing a one-way sailing (such as a southbound Alaska cruise or a trip from Barcelona to Rome), you might want to consider choosing a cabin on the side of the ship that faces the land. Sometimes the views can be breathtaking, and you would not get those views from the cabins that face out to the open sea.
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.