These are not predominantly Viennese Waltz balls, but most have a fair amount of Viennese Waltz. Some are hosted by the city, others by occupations, churches, organizations etc. Their balls are nearly all black tie events with ladies dresses required to be at least ankle length. Ladies wear mostly modern ballgowns, and only debutantes wear white ballgowns. At larger balls food is available at a buffet that is open all night long.
Most balls are too crowded for good dancing though some are marginally OK late in the evening.
There are large differences in the many ballrooms around the city. The main ballroom in the Hofburg palace is 200 years old and of stunning marble construction. The paraffin wax on the wood parquet floor is too slick for good dancing. Parkhotel Schonbrunn has a small elegant ballroom with perfect friction for dancing. The ballroom in the Rathaus looks like the nave of a Gothic cathedral.