Vienna has an extensive public transportation system, including buses, trams, and the U-Bahn. A 24-hour ticket is €8.00 and includes unlimited travel on all modes of transportation. Taxis are also readily available, but more expensive. The travel time from Vienna International Airport to the city center is about 30 minutes and costs around €30 in a taxi or €5 on public transportation.
If you have more time, consider visiting the Vienna Zoo or taking a day trip to Salzburg. If you have less time, cut out the day trip to Bratislava and spend more time exploring Vienna's historic center.
Viena International Airport (VIE), is located 18 km southeast of Vienna. It is the largest and busiest airport in Austria. It offers several transportation options to the city center, including taxis, car rentals, and public transportation (S-Bahn or CAT trains).