The newest hotel on WDW property is the
Saratoga Springs Resort and Spa, which opened in 2004. This is a
Disney Vacation Club property and not an officially a deluxe resort, but it does have a fairly sophisticated feel to it. For "official" deluxe hotels, the newest is the
Animal Kindgom Lodge, completed in 2001. The other deluxe resorts were opened in this order: The BoardWalk Inn 1996; Wilderness Lodge 1994; Yacht and Beach Club and the Swan and Dolphin 1990; Grand Floridian 1988; the Contemporary and Polynesian 1971.
I'm not sure that I would base my decision on where to stay on the age of the hotel alone. Disney does a very good job of keeping the rooms fresh and does renovation whenever necessary. All of the deluxe resorts are wonderful. I would choose my hotel based more on my theme preference. For example, the Grand Floridian is elegant, the Wilderness Lodge is woodsy. Which atmosphere make me more comfortable? Another way to choose is to look at the unique amenities of the hotels: the Yacht and Beach has the best pool and is close to Epcot; the Polynesian has monorail access and is close to the Magic Kingdom, which suits my needs better?
By the way, the hotel opening information and lots of other great Disney trivia can be found at
www.wdwmagic.com.