The Guggenheim estate IS Falaise, so I guess that's where the interiors were shot.
Funny, most books on the subject, including Harlan Lebo's, list Woltz's home as the Guggenheim Estate.
If you look at this link, it doesn't appear that Falaise looks like the exterior of Woltz's home, but the interior shot looks like the dining room that Tom and Woltz had dinner.
