Many cruise lines offer packages that include airfare in addition to the cruise. These flight packages have significant advantages, as the cruise line takes full responsibility for getting you from the flight to the ship. If any issues arise, the cost of flight changes or rebooking is handled by the cruise line. In addition, these packages usually include airport-to-port transfers and return transportation at the end of the cruise.
The main drawback is that these packages are generally more expensive, but in some cases they can be worth the price.