The Monaco-based luxury cruise line Silversea has launched Silversea Grand Expeditions—a group of five new itineraries for fall and winter. Each trip starts at about $11,000 a person and kicks off with a cruise around the Galápagos Islands before heading along the coast of Central America, South America, or Antarctica. Ranging from 18 to 34 days, the packages include cruise fares for the ships Silver Galapagos and Silver Explorer, land tours,  hotel accommodations, return air travel, and ground transporta…