Melinda has a great apartment in Vienna, we've used air bnb on a number of occasions, Melinda communication was the best yet.
The apartment is perfect for 2 people and has good transport links to the city centre, it also has the bonus of a balcony.
We had a great time in Vienna, our favourite site was the Kunsthistorisches Museum, one of the best we've ever visited. Its worth trying to get tickets for the opera/ballet at the Staatsoper, a great night out followed by a bite to eat at the nearrby sausage stand and a posh drink at the Sky Bar on the roof of the Sofitel.
Also would recommend a day trip to Bratislava, you can get the boat there and the Train back