On paper, Norwegian Luna — with its over-the-top roller-coaster-waterslide, thrilling 10-story free-fall slide, and high-tech mini-golf course — might sound like an overstimulating cruise ship. Yet, when you step on board the new 1,056-foot-long vessel, you'll quickly realize it feels more like a peaceful upscale hotel than the overwhelming family vacation you were secretly dreading. That's the beauty of Norwegian's Prima Plus -class ships, including Luna and its preceding sister ship, Aqua: the ability to blend contemporary spaces with an impressive lineup of amenities, making it a great option for cruise-curious travelers. It's why Norwegian Luna has become one of my go-to recommendations for first-time family cruisers. The Glow Court's LED walls and floor can transform the space. Brittany Chang Norwegian invited me on Luna's complimentary three-night non-revenue test cruise in late March, almost a year after I first sailed on (and loved) Aqua.…