Holland America
Holland America was the first cruise line to offer service to Alaska, and according to some polls it may still be the best. The recently launched Expedition Tours series puts travelers on small boats that ply Alaska's remotest ports. Holland America's train service allows passengers to combine boat travel with visits to Denali, the Yukon, and the Klondike. One to three-week long cruise tours are available. Holland America tends to cater to up-market travelers with high expectations for food and service.
http://www.hollandamerica.com/main/Main.action
Royal Carribean
Royal Carribean's 10- to 14-day cruise tours combine travel on a fully outfitted Royal Caribbean ship with a trip on the Wilderness Express, a glass-domed train car that journeys through the Alaskan interior. Royal Carribean ships are large (3,000+ passengers), which prevents them from visiting Alaska's remoter destinations, but they are outfitted with casinos, multiple restaurants and the other entertainment features travelers have come to expect from one of America's largest cruise lines. Prices are affordable, and amenities are specifically designed to provide entertainment for all ages.
www.royalcaribbean.com
Princess Cruise Lines
Princess carries the luxury of ship-board living into the heart of Alaska with its privately operated series of wilderness lodges. Lodges are accessed by Princess operated trains----the only in Alaska to have open air observation decks. Each wilderness lodge is state of the art, complete with fireplaces, jacuzzis and outdoor activities. Princess ships are elegant, featuring onboard art galleries and cuisine inspired by Alaska's natural abundance of ingredient. The company tends to cater to couples, with special services available for weddings and anniversaries.
http://www.princess.com/index.html