Tours are arranged by the Frank Lloyd Wright Trust. The best tour may be the Wright Around Oak Park tour that goes to his House and Studio, Unity Temple plus 10 other Wright homes in Oak Park! Those 10 are exterior only - presumably private residences. Walking tour with a limit of 10 people. It is about 3 hours long and costs $60.
There is also a biking tour available (bicycle provided) called Pedal Oak Park that visits 21 Wright-designed structures. It is about 2 hours long and costs $45.

Probably the best place to stay while on a tour is the Lang House and the Emil Bach House which are renovated FLW designed homes. Booking is available through their website.