Vienna is really nice. The whole town is lovely, clean, green and well organised. I have been here on two occassions now, and the below is a summary of both combined.
The Imperial palace was really good, very pretty. It has such a grand presence. The buildings there are very well looked after and very cool. The associated gardens are very well taken care of, although I find it a bit odd (even after all this time) that you are not allowed to sit on the grass and enjoy the gardens properly.
So hard to describe how weird it felt being in such place, surrounded by grandeur. The parliment building was so white and clean. There was clean gold statues everywhere.
A big highlight was going to the cemetary in Vienna where I visited Beethoven, Schubert, Struass, Brahms, and the memorial to Mozart. The cemetary should actually be on peoples must do list here, as the bascilica in the centre is actually extremely interesting, with the bold clashes of colour and is actually really good for singing in.
In the surrounding suburbs are a number of other smaller or summer homes that are now within Vienna borders. It is unfortunate that the palace zoo is too expensive to warrent the visit.
The permanent circus grounds are a must do attraction in Vienna. Went on a ferris wheel that showed the whole of Vienna from it. Had some lovely weiner schnitzel there and just goofing around on some of the rides. It is also right in the middle of an amazing park which I once went to a couchsurfing conference in. This area is amazing even in winter.