One of—if not the most—cleanest, safest, most expensive cities in all of Europe. I'd always spend the day in Vienna first, before making my way to Budapest—one of the dirtiest, most dangerous cities—if you're getting around the city by train—cheapest—save for its Balkans neighbors—in all of Europe.
Vienna also plays host to one of the greatest Asian restaurants I've ever been to—more so during the winter months when it'll serve Murauer Bock beer. Who knew? Old school Austrian Bock beer goes extremely well with fine Asian cuisine.