For more than 80 years, AAA has used professional inspectors to conduct anonymous, in-person property evaluations. AAA offers the only rating system using comprehensive, on-site professional hotel and restaurant evaluations guided by member priorities. With a far greater inventory than any other rating entity, AAA’s rating system covers the United States, Canada, Mexico and the Caribbean.
Each year AAA reviews nearly 28,000 hotels – Just 0.4 percent make the AAA Five Diamond list and The American Club Resort in Kohler, Wisconsin! 
Just 5.9 percent of the nearly 28,000 hotels Approved by AAA make the Four Diamond list. The properties below were named Four Diamond Hotels:
- The Delafield Hotel, Delafield
- The Osthoff Resort, Elkhart Lake
- The Edgewater, Madison
- The Charmant Hotel, La Crosse
- Grand Geneva Resort & Spa, Lake Geneva
- Hilton Milwaukee City Center, Milwaukee
- Milwaukee Marriott Downtown, Milwaukee
- The Iron Horse Hotel, Milwaukee
- The Pfister Hotel, Milwaukee
AAA Diamond Ratings for hotels represent a combination of the overall quality, range of facilities and level of services offered by the property. The descriptive ratings are assigned exclusively to properties that meet and uphold AAA’s rigorous Approval standards.
Source - http://newsroom.aaa.com/diamond-ratings/
