A few decades ago, a nicely appointed library was one of a cruise ship’s star attractions. But then came climbing walls, ice-skating rinks, hand-carved carousels, 4-D theaters, zip lines and surfing simulators. Plus e-readers, tablets and smartphones. That spacious mahogany library stuffed with thousands of volumes suddenly had lots of competition. Some lines, such as Disney, which launched in the late 1990s, decided to forego libraries altogether. Others, including Carnival and Seabourn, dressed them up with wine bars and coffee stations. And a few, such as Cunard and Oceania, have stayed with tradition.