On many ships, basic inside and outside cabins are usually the same size, the difference being that one has a porthole or picture window to let in natural light. Balcony cabins can also be the same size as standard insides and outsides, with the addition of the outdoor space on the verandah; sometimes the interior space is larger. A basic cabin, regardless of category, is referred to as a "standard" unless there is something about it that makes it different (such as physical layout, being handicapped accessible or a designated family cabin). With minisuites on up, you get bigger and bigger indoor and outdoor spaces.
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.
Having a personal butler can be a wonderfully pampering experience, and some cruise lines include the butler service as part of your fare when you select a suite or "concierge level" cabin. Look carefully at the difference in the cruise fare, and decide if it is really worth it. Beyond that, look at the services that are offered; some cruise line butlers really do provide extra value. For instance, some can bring you room service from hard-to-get-into alternative restaurants, refill your mini-bar to personal specifications, and serve in-cabin meals course-by-course. Butlers can also unpack and repack your bags, draw rose-petal baths and assist you in preparing in-suite cocktail parties.
Inside cabins: These cabins are usually the lowest price. Typically they will have twin beds that convert to a queen size, a private bath with a shower, a closet for hanging clothes, a dresser and a television. These cabins do not have a window to let natural light in. To help give the occupants an impression of having a view, some inside cabins have a virtual view. That means there is a large screen that displays outside views. Expect to pay $100 to $200 a night for an inside cabin.