A concierge can take care of all those annoying practical matters you need to tend to on a cruise: making dinner and spa reservations, booking shore excursions, making requests of the front desk. Their services are included in the price of many suites, and on some ships the concierge has a desk in an exclusive concierge lounge where suite guests and high-level past passengers can snack, drink and relax in private. Concierge-level cabins may also come with in-cabins amenities including welcome drinks, fruit baskets or afternoon canapes.
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 with no views at all are typically the smallest, cheapest cabins onboard. They are great options for budget-minded travelers who do not intend to spend a lot of time in their stateroom, or who want to sleep all day in absolute pitch dark. They are less ideal for cruisers prone to seasickness, those who need natural light and groups who require a lot of in-cabin space. Not everyone will be happy in an inside cabin; it is worth upgrading if the lack of light will put a damper on your vacation.
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.