With so many sexy ships to choose from, what really makes a cruise ship luxury? We stepped aboard to find out

I once asked a venerable cruise critic what constitutes a “luxury cruise,” since some of the most expensive (and expansive) windows at sea are on the big ships.You can plunk down $40,000 a week for Celebrity Edge’s Iconic Suite, or even $150,000 a week for the Ultimate Family Townhouse on Royal Caribbean’s vast Icon of the Seas.But, “Luxury,” he said, “is where other people aren’t.”He has a point.

On the aforementioned ships, you’ll have 3,500 to 5,600 neighbors, respectively.In contrast, the luxury branded, smaller ships offer a more village atmosphere of 200 to 600 or so, with a high ratio of staff to cruisers (think 1:1, or better).Additionally, you’ll often find these lines more attractive to solo travelers who don’t want to be surrounded by (and feel excluded from) big groups, so even a sold-out sailing doesn’t equate to full capacity.

That means ample chill spaces and pool loungers, and a sense of calm versus cacophony.The boutique Seabourn line, with just five ships, including two expedition cruisers, fits that less-is-more ethos, placing an emphasis on unfussed luxury where almost everything comes included in the sticker price — something else luxe travelers want.That includes caviar at your beck and call, and lashings of Champagne, which is liberally offered at every opportunity.

In fact, you’ll rarely be far from a popping cork.(Guests quaffed some 145,000 bottles of the stuff across the fleet last year.)On a seven-day “Yachtsman’s Caribbean” trip on Seabourn Ovation (from $3,329 per person), the neater ship size also means the itinerary can live up to its title, cruising from St.

Maarten to Barbados via the British Virgin islands, St.Kitts, Martinique, Grenada and St.

Vincent and the Grenadines, all the while bypassing touristy big towns and industrial dock views in favor of anchoring out in scenic bays, overlooking hillside villages and lush vistas.“Every morning I had a ‘throw those curtains wide’ moment,�...