I'd been on the world's longest megaliner, Allure of the Seas, for two days shortly after it launched in 2011. As I rode a glass elevator up, up, up through the ship's expansive atrium, two women chatted about how much they loved the ship.

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"You know," one excitedly said, "I haven't even seen the ocean yet!"

To some, that might be the ultimate indictment of the new trend toward cruise ships such as the Allure, which could contain five Titanics. But for those women, sailing the Caribbean on a floating megalopolis (that atrium, named Central Park, boasts a tree-studded, football field-size glen with a meandering path) was perfect.

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I long ago decided that when you figure in the costs of lodging, food, and transportation, cruising is by far the most economical way to see the world in comfort — even with a family in tow. What's more, because cruise ships come in all shapes and sizes, if you scan the horizon long enough, you'll spot a vessel that's perfect for you.

Megaships

2,500 to 6,000 passengers

You should pay: From $79 to $155 per day inside; $129 to $170 per day ocean view

(Norwegian Breakaway, Queen Mary 2, Carnival Breeze, Disney Fantasy, Royal Princess)

The best news for vacationers is this: More cabins require more passengers, and given the current economy, that means megaship deals are getting easier to find. After reigning as one of the Caribbean's most expensive ships a year ago, Oasis of the Seas is down to just over $100 a night per person.

Target Travelers
"Families take over these cruises," says Carolyn Spencer Brown, editor of Cruise Critic (cruisecritic.com). "There's something for everyone."

Entertainment
In the 1980s I sailed on Royal Caribbean's upscale Song of Norway, and one night's featured entertainment was, no kidding, a guy playing the entire 1812 Overture on an accordion. Today's megaship features at least one Broadway-type theater — and a show to match: Royal Caribbean has been staging the musical Chicago, and a How to Train Your Dragon ice show while the Queen Mary 2 offers a domed star show created with NASA. For quieter pursuits, Holland America’s Eurodam has paintings by Dutch masters and the line’s Rotterdam features exact replicas of China’s famed terra cotta warriors.

Pools
Take your pick: You'll find at least two and as many as five.

Cabins
Even on the biggest ships, cabins aren't much larger than the one the Marx Brothers spilled out of in A Night at the Opera. But the days of little portholes are gone — in an outside cabin, chances are you'll enjoy a nice balcony or large windows. What’s more, Disney has given a new life to those formerly dingy inside cabins: On the cruise line’s newer Dream and Fantasy ships, above the bed you’ll find a “virtual porthole” with a high-definition screen behind it. Cameras mounted up on deck beam the outside view all day long, and the result is an uncanny sense of seeing a live through-the-glass view.  

Dining
You can still head to the formal dining room, but the biggest ships pride themselves on offering countless dining options, from sprawling buffets to poolside grills. You'll also find premium restaurants that offer a fine dining experience worthy of a big city — for a reasonable extra cost. The gourmet menu at the Disney Dream’s Remy Restaurant — yes, named after the rat in Ratatouille — will run you an extra $75, but it was created by 2-star Michelin chef Arnaud Lallement of Riems, France. At Holland America, all 15 ships have menus created by a “Culinary Council” that includes such chef/authors as Rudi Sodamin, David Burke, and Charlie Trotter.

Destinations
Because of their size, megaships largely stick to ports with big facilities — places like the Bahamas, Mexico and the Mediterranean.