Old Westbury Gardens

We went there on in mid July and it was really amazing (a little hot but not too bad).  The grounds are huge, there is a lake and its all really crazy.  The pool was one of my favorites and the house tour is done by some really talented staff.  There is a pretty sizable pond and even bigger lawns, some walking trails that are fun, but the house and its immediate grounds (gardens, pool and such) are the reason to go IMHO.  They do concerts here outside on the patio, but the one going on while we were here was for kids (I hope it was that, anyway).

The house was built by John Phipps, who was a partner with Carnegie.

Its a fairly short drive here -- maybe an hour or so out on the gold coast.