Port of Miami

On a recent Saturday afternoon onboard the Norwegian Epic cruise ship, Dennis and Julie Solet peered into a luxurious lounge outfitted with velvet couches and gauzy curtains. But after the Solets told an employee they weren't staying in a suite, the couple was turned away. The lounge, a small sign said, was reserved "for suite guests only."

"Money has its privileges," said Mr. Solet, a 62-year-old retired teacher from Windsor, Ontario. "One day we'll be suite people."

There is a new cruise ship class system. A growing number of cruise lines have built lavish—and separate—cocoons for their biggest spenders. It is a departure from the egalitarianism that had reigned on most ships for the last several decades when everyone from those staying in the humblest inside stateroom to those in the most luxurious suite would rub elbows in the same bars, dining rooms and pool decks. In a way, the trend is a throwback to the heyday of trans-Atlantic crossings in the 1920s, when first-, second- and third-class passengers were assigned separate areas of vessels. (Though no one would mistake today's cheapest stateroom for the gloomy steerage dorms of centuries past.)

On the 4,100-passenger Epic, which started sailing last June, guests in the 75 Courtyard Villa suites have a private restaurant, fitness center and pool, where employees pass out fruit and spray sunbathers with cool water. On the two-month-old Disney Dream, passengers in the 41 rooms on the concierge level have the sole use of a sun deck and lounge with free food, booze, fancy coffee (other guests have to pay $2.25 for a small cappuccino elsewhere) and loaner iPads.