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...