Interesting thread. Don't know that I've ever done anything 100% unique. I probably have some limited experiences, that only a few have done, and the combination is rare.
Driven trucks, modern tractors, antique tractors, motorcycles, combines, cotton strippers. Piloted small aircraft, including the relatively scarce Bellanca Viking and have ridden in sailplanes and military and civilian helicopters, plus a ride in an O-2, in which I barfed. Have visited at least 5 AF bases and one Army Post.
Been to Trinity Site, Los Alamos, Oak Ridge, K-25, Sandia, and to the town of Savannah River, but not the facility. Have (legally obtained) nuclear bomb fins and lift lugs.
Wife works in a classified area and has worked on nuclear weapons. My dad met George and Jeb Bush at an American Ag Movement protest in the late 1970s. George was running for Congress, Jeb was along to help. Daughter in law taught ice skating to Chuck Norris's daughter. Son has been underwater in a nuclear submarine. Son in law owns a share of an ammunition company.
I'd say the only thing I've done that it's almost 100% sure that no one else has done, is to raise a girl who became a fighter pilot.