I used to work at the Biltmore–man, that was a weird gig, Dilbert meets Martha Stuart. Keep in mind that the Estate is run as a profit-making enterprise. Their primary purpose is not to educate or preserve history, but to make mega-bucks. They will gouge you for every penny.
A winery tour and tasting is included in the price of your ticket, so definitely check it out and try the free booze. The wine is mostly mediocre, and you can buy Biltmore wine more cheaply at local grocery stores, so don’t buy it at the winery.
The float trip is lovely and worth doing. There are also lots of trails around the property.
The Estate is still run by the family, so you’re not going to hear anything juicy on the audio tour–like the fact the Mrs. Vanderbilt forced her young daughter Consuelo into a loveless marriage with an English nobleman in order to bring a title into the family. It’s a lot of “This wallpaper was designed by so-and-so.”
Be prepared for lots of cranky, hot crowds. If you buy your ticket after 3 pm, you can get in the next day for free. If I were you, I’d do that. Try to do the float trip in the late afternoon, followed by the winery tour. Come back early next morning to do the house and garden tours. (You should call and double-check that “after three, next day free” is still the policy.)
The restaurants are meh and over-priced. For a truly killer meal, try Zambra in downtown Asheville.