Carnival: You can find itineraries for less than $100/night. Access to the ships' pools, water parks, mini-golf courses and evening entertainment won't cost you more than your standard fare.
Celebrity: You can find itineraries for less than $100/night. The line also shakes up the dining standards, allowing guests their pick of specialty dining venues for one flat package rate; meals at the main restaurant are covered in the cruise fare.
Norwegian: You can find itineraries for less than $150/night. And though meals at specialty restaurants will cost extra, several eateries across the fleet offer dining for as low as $20 per person.
Holland: You can find 7 day itineraries for less than $100/day. Each ship houses one staff member per every two guests, Holland America offers more personalized service than many of its mainstream competitors.
Costa: Still recovering from heavy scrutiny after the Costa Concordia accident in 2012, this fleet continues to offer rates that are considerably lower than usual. Although there are family-friendly amenities, Costa is better suited for adults and offers dance and language classes, a library and evening theater productions, all of which are included in the cruise fare.
MSC: MSC will allow you to experience destinations around the world at extremely reasonable rates, with cruises around the Mediterranean, northern Africa and South America costing less than $100 a night. In addition to dining in many of the onboard restaurants and access to facilities like pools, cinemas and bowling alleys, MSC rates also cover fitness classes and gratuities.