Wright-designed buildings the Frank Lloyd Wright Building Conservancy lists as open for overnight stays, narrowed to the ones you can book on the house's own site.
The standard is the Frank Lloyd Wright Building Conservancy's own Wright Overnight Stays list, narrowed to buildings that take bookings on their own website or their owning nonprofit's site. It is the Conservancy's list, not ours.

Frank Lloyd Wright built about four hundred houses and a handful still take guests for the night. The Conservancy that tracks his surviving work keeps a public list of the ones you can sleep in. Most of them rent only through Airbnb or VRBO. This club is the shorter list of the ones that book direct, so you deal with the cottage conservancy, the family, or the hotel itself.
Seven stays, six houses and one hotel, from six operators across Wisconsin, Pennsylvania, Ohio, Oregon and Iowa. Each links to the operator; you book with them.
Preview from Still Bend's listing
Preview from Polymath Park's listing
Preview from Polymath Park's listing
Preview from The Historic Park Inn Hotel's listingThe Conservancy lists 15 buildings. Eight of them rent only through Airbnb or VRBO, or could not be confirmed as bookable at all, so they fail the second test. Several candidates are not on the Conservancy list or are closed.