Vienna has an extensive public transportation system, including underground trains, trams, and buses. The easiest and most cost-effective way to travel around the city is to purchase a 24-hour or 72-hour ticket, which allows unlimited travel on all modes of public transportation. Taxis are also available but can be pricey. From the airport, it is recommended to take the City Airport Train (CAT) or the Vienna Airport Lines bus, both of which take approximately 20 minutes to reach the city center and cost around € 12.
If you have more time, consider visiting the Hundertwasserhaus, a colorful and eccentric apartment building designed by the artist Friedensreich Hundertwasser. You can also take a day trip to the nearby city of Salzburg, which is known for its stunning architecture and the birthplace of Mozart. If you have less time, consider skipping the Danube River Cruise or the Vienna State Opera if you are not particularly interested in those activities. Additionally, try to book attractions such as the Schönbrunn Palace and the Vienna State Opera in advance to avoid long lines and potential sellouts.