And of space stations, don't forget the very successful Salyut program , which broke many records, some which still stand. All seven single-module Salyuts have been de-orbited after completion of their missions.
The last two Salyuts had more life in them. Salyut 8 became the core module of Mir (now deorbited).
And Salyut 9 is still alive, as the Zvedza module of the ISS !
Skylab wasn't really targeted -- it deorbited completely uncontrolled. Controllers had intended to deorbit it into the Pacific, but there had been delays in the Shuttle program (which was meant to attach a deorbit module to it) and the upper atmosphere was more active than normal, for reasons which are understood now but were not as well understood then. It fell long before Shuttle could have saved it or even aimed it, alas.
If you ever visit Washington, DC, go to the National Air & Space Museum. Skylab 2 was never launched, and instead was donated to the Smithsonian. Holes were cut in its sides to allow people to walk into it, and platforms were built so you could walk around. Most people think it's a model, but it's not -- it's an actual spacecraft, but one which was never completed or launched. With the cancellation of Saturn V, there was no way of getting it into space.