I saw the United States in Philly a couple years back -- just sitting forlorn. Restoring and maintaining ships is a monumental undertaking -- it makes aircraft restoration look easy. The biggest problem being that anything that sits in the water is going to require a lot of maintenance. I've read articles that while Yorktown looks good on the outside, the hull is not in very good shape when inspected from the inside.
Two of the more heartbreaking stories IMHO was how the USS Cabot slipped through everyone's fingers. Other than island structure, she was basically unmodified from her World War II configuration and the only surviving CVL. The group that took her over after she left the Spanish Navy completely dropped the ball and went bankrupt. There were plenty of places it could have gone, but at the time Baltimore and Tampa were fighting for the rights for the Forrestal, which neither one ended up with it. At the end, someone only needed to put up $130,000 to save it, and it couldn't be done. The other one was the USS John C. Rodgers which was one of the rare "High bridge" Fletcher class destroyers still in its near original World War II configuration in the Mexican Navy. Again, a group was trying to save the ship, but fell short in its efforts and the Mexicans ended up scrapping it.