Choosing a world cruise is a monumental decision that requires balancing itinerary diversity, ship size, and "vibe." First, look at the route: "Full" world cruises typically last 100 to 180 days, but they vary in their focus—some prioritize "slow travel" with overnight stays in hubs like Tokyo or Sydney, while others emphasize "breadth" by visiting up to 50 countries. Second, consider the vessel. Smaller, luxury ships (like those from Silversea or Seabourn) can access boutique ports that large mega-ships cannot, offering a more intimate, adult-focused atmosphere. Larger ships (like Cunard’s Queen Mary 2) offer more robust entertainment and ballroom dancing but can feel crowded during the long months at sea. Third, evaluate the "included" value; look for packages that bundle business-class airfare, laundry services, and gratuities, as these costs can skyrocket over a four-month voyage. Finally, research the "lecturer" program, as high-quality guest speakers can significantly enrich your understanding of the diverse cultures you will encounter along the way.