If there's one thing that Newport, Rhode Island is famous for, it's for the mansions with gorgeous ocean views and lavish interiors. Touring these buildings has become quite an attraction, and you can visit a good majority of these through the Newport Preservation Society. We got a pass to allow us to visit 5 mansions (although we were only able to do 4 in the day).
The top one to visit is the Breakers, which was built by the Vanderbilts. It's difficult to put into words what the interior or exterior of this mansion looks like, but let's just say that everyone in your group will be impressed. When entering, you're also given a set of headphones for a self-guided audio tour, which was quite enjoyable and gave you a great understanding of the history of the building and its former residents.
We also got to tour the Elms, Marble House and Rosecliff on this day, which were all impressive as well. They all came with self-guided audio tours and you got a great appreciation for what life in Newport in the Gilded Age was really like. From the backyards of all of the mansions, you'll get great views of the ocean (except the Elms, as that is on the opposite side of the street) and a great place to just relax for a while. The Marble House also has the Chinese Tea House in the backyard, which is a convenient place to stop for lunch during the day.
Exploring these mansions is almost a must-do when visiting Newport and is quite enjoyable. Also, to make this more convenient for tourists, each mansion does have its own parking that is free.