Hilton has three hotels in Vienna. Two are downtown, but only the Vienna Plaza is open currently, the Hilton Vienna is under renovations. The Hilton Danube is located on the other side of the river just past the Prater and is only a short tram-ride to the city center. It is not as fancy as the Hilton Vienna Plaza, but it tends to cost much less, so it may be worth considering if you are on a tight budget.

FOr more information on what to do and see, etc., check here:

www.flyertalk.com/travel/fttravel_forum/Forum33/HTML/000483.html

Have a great trip, Vienna is a wonderful city.