The appeal of a family cruise isn't hard to understand: Why go through the trouble of moving from hotel to hotel or place to place when you could check in to a floating resort that moves with you? Different cruises come at different prices and offer their own services. Some allow children to board for free; others have nurseries or clubhouses just for teens. Do your research ahead of time to make sure the cruise you want provides the amenities — and discounts — you're looking for, no matter where in the world it goes.