Pension Suzanne is very central -right opposite the State Opera House and near the U-bahn. We had an apartment which was quiet with everything one needs including a little kitchen. I'd recommend it even though it's not cheap. The people that ran it were very helpful, the buffet breakfast was adequate and the apartment was very clean.
Vienna is beautiful - the baroque architecture, the art galleries and the Danube on which a trip will take you past mediaeval villages. Best of all for me was the music and it's history (masses of enlightenment music in the churches, including Haydn, Mozart and Beethoven) the tour of the Opera House and the boat trip on the Danube to an old abbey. Best for my grandson (16) was the history, afternoon tea at the the Hotel Sacher for Sachertorte and hot chocolate and the boat trip.
I'd go back like a shot but at a time when the opera house was open!More