Took my wife and daughter to a Saturday Landmarks Tour. This is a FREE 2 hour tour of the Frank Lloyd Wright designed Administration building and (forget the designer) Fortaleza Hall. We really enjoyed it.
Reservations are very easy online, although we had to book a month in advance. Questions are answered very promptly by email. The staff on site were very welcoming, like you walked into their home.
The tour was excellent. This is a gorgeous corporate campus, meticulously maintained. I've seen many FLLW designed homes, the Admistration building is simply amazing, it must really be seen to be appreciated. I'm a huge fan of what he was able to envision and accomplish over 70 years ago - nothing like the boring office boxes built today. On Saturdays you get to see the executive 3rd floor, an extra bonus. The central tower in the complex is not part of the tour, not all of FLLW's designs were practical and the tower doesn't meet newer occupancy codes.
The tour guide was very knowledgeable, helpful and friendly. You are on a "factory tour", so you get background on the Johnson family, the company, and its products. To me that is also what makes the tour complete, their story is very much entwined with Wright. I would highly recommend this.
Don'f forget to grab a Kringle on your way out of town, its a local specialty at a few local bakeries.