We had a lovely stay at Farhud's apartment just outside the centre of Vienna. Close to public transport and everything you could possibly need. The only downside would be that the apartment does heat up quite a bit on warmer nights, and the traffic can be pretty noisy if you leave the windows open to relieve the heat. But I would imagine this is only on the really hot summer days. Apart from this small negative Farhud's place really does make for a perfect base to explore Vienna!