arawal, I'd suggest a search of 'Vienna' as these hotels have been discussed here several times in the past. As a short synopsis, the new Danube property is supposedly nice but the location is lacking as it's across the river not in the city center. The regular Hilton and the Plaza both have equally good locations near the city center. The Plaza is somewhat smaller but also newer and nicer. I had a wonderful stay at the Plaza, but from posts here the regular Hilton sounds good as well.