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.
For some reason, most cruise lines assign their nicest and most expensive cabins to the highest decks, usually just below the pool deck (most likely because if you have a window or balcony, you have a more sweeping vista). Still, it is the pool deck that often causes the most noise problems, so if you do not want to hear scraping chairs at the crack of dawn or yee-hawing pool parties until the wee hours, go down a level. In fact, when it comes to noise, the best bet is to select a cabin that is both above and below other cabins.
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.
You can also use our drag deck feature to determine if your cabin is in a good location. Cabins are best located when they are next to, above or below other cabins. As a rule of thumb avoid booking a cabin under a public area or kitchen. If you are looking for a balcony cabin, please be aware that on many ships the cabins that are below the pool deck may also be shaded by a roof overhang from the deck above. You can also use our drag deck feature to determine if there is a overhang.