It is truly a stunning architectural achievement. The house and grounds are beautiful. Being a sucker for historical tourism, I signed us up for both the Architect's Tour and Butler's Tour.
For the former, it was just our family and the tour guide. She regaled us with details of the construction and design while taking us to all sorts of places not on the standard tour, including the roof!
For nerds like me, it was fascinating. The girls and Tim liked it too and Eion tolerated the whole thing pretty well, though he told us he was not going to learn anything. Fair enough E, just be quiet about it.
After we finished the Architect's Tour, we went through the remainder of the house and the gardens.
The tulips had bloomed early because of the warm winter so we missed those, bummer. But it was still impressive. Having loved the first tour, I bribed the children with the promise of ice cream and we went on the Butler's Tour which was all about how the back of the house ran - the boiler room, the servants' quarters, the kitchen, the electrical system. Again, well worth the extra cost and so interesting. Eion was near fully baked at this point but ice cream is a powerful motivator and he disrupted the tour not a whit.
It was a great day. If you are planning on going and either aren't taking the kids or have kids that will tolerate it, I would recommend the whole package. For $150 (each, additional, I know it is steep) you can do the two tours we did, plus a grounds tour and additional house tour. I would have done more but we had already pressed our luck.
We went to a new section that has been built in the last 10 years or so. They took what was the dairy and turned it into a winery and a little farm. You should skip this entirely. The "winery tour" was a trip through an underground tunnel which dumps you in a large tasting room connected to a gift shop. And while they will give you grape juice (of the very staining variety) for the kids, they aren't allowed to sit next to you and have to sit on benches behind you.
The "petting zoo" is pretty much chickens who are not interested at all in being petted. Watching Eion stalk them, unsuccessfully, was entertaining, but not worth the extra hour at the end of our day. Antler Village and Winery would be better entitled, Bilmore, The Quest for More Cash.
But even with the Antler Village disappointment, the day was a rousing success.