Wien (Vienna) is the ONLY major city I could ever see myself living in. It has a population of 1.5 million, but it still feels to me like a friendly and much smaller city. The architecture, history, music, and overall ambience is fantastic. Stephansdom, Schönbrunn Palace & Zoo, and the Hofburg are all must-sees. Don’t spend less than a week in Wien or else you’ll miss out on all it has to offer.
Hotel Sacher, in my opinion, is overrated—try going to some smaller bakeries more out of the way. Sacher might claim to have the ‘original’ Sachertorte, but it’s ungodly expensive and isn’t as great as it’s said up to be. If you’re into shopping, definitely take an hour (or two) (or three) on Mariahilferstraße—expensive, but worth it. I reccommend spending an afternoon or evening just walking through the first district by foot—there are usually street artists & performers, it’s a good way to check out all the shops and cafes, and it’s just a nice way to soak up the culture there.