The Wolfsonian is the brain child of Micky Wolfson, who started not only this museum, but another like it in Genoa Italy.
The museum is unlike most others. It focuses more on art and design from the period from about 1850 to 1950. You are unlikely to see works by Manet or Van Gogh, but it does have countless artistic design items ranging from posters to furniture to unusual objects. The exhibits change every few months, so the exact things on display will vary as well.
The building itself is historic and they have added many design elements, such as a cool Art Deco elevator and many others. The museum is currently undergoing a renovation and expansion. You can still see two floors of displays, but some of the items are on floors that are undergoing construction. When the construction is done, there will also be a display library of sorts for visitors.
The current exhibition focuses on the idea of aerial views, which would have come into being mostly after the invention of the airplane. The exhibition includes vintage posters, futuristic (for the early 1900s) versions of what might come, and many cool objects. One mural/large painting depicts Miami around 1920, with emphasis on new developments that are now around a century old. Another is an enormous globe chandelier with fun elements that include mermaids. The exhibits are artistically designed so you won't just be looking at objects in cases or hanging on a wall.
Take a look at the ceiling on the top floor. It looks like it came out of a medieval castle, but it's really from an automobile dealership. You can tell because elements like wheels and steering wheels are part of the design.
The Wolfsonian is a very easy walk from Ocean Drive and the center of Miami's Art Deco district. It's a fun stop and you will certainly see things you have never seen before.