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.
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.
When it comes to choosing suite accommodations, it is best to figure out how much space you really need, what amenities are important to you and what you can afford to spend. Suites on most ships are often the first category to sell out, partly because there are fewer of them, and partly because they often offer extremely good value. For this reason, it is important to decide early what kind of suite you would like.