Here's a summary of my own experience at a few 5 star hotels in Vienna,
bhrubin. (I've stayed more than once at most of them). I can't comment on the aircon as we Europeans don't care much about it (and in Vienna you don't need it anyway most of the time, definitely not in October). Hopefully you'll find the following useful.
Imperial:
-5 star accommodation: Historic building and a typical Classic Luxury property.
-Service: very good.
-Authentic Viennese flair: Definitely.
-Dining: Restaurant Opus with 1 Michelin star is very enjoyable.
-Summary: Very Viennese. Classic, historical style throughout the hotel.
Park Hyatt:
-5 star accommodation: Design-oriented luxury hotel (typical PH). Beautiful classic building (former bank HQ).
-Service: very good (especially the concierge who snatched a last minute table at Silvio Nickol for me).
-Authentic Viennese flair: yes but a modern interpretation of it.
-Dining: The Bank Bar & Brasserie is one of the most visually stunning places in the city and serves great food.
-Summary: Great hotel but don't expect a historical Viennese style.
Bristol:
-5 star accommodation: yes but the hotel has an ugly entrance with cheap shops (and even a Fashion TV Café in the same building) on the ground floor. To me this ruins it.
-Service: good.
-Authentic Viennese flair: yes but there are better options.
-Dining: nothing to write home about
-Summary: The rooms are quite nice and I wanted to like the place but in my book it's just not a real 5 star luxury property.
Palais Coburg:
-5 star accommodation: yes but a bit of a quirky mix between classic and contemporary.
-Service: very good.
-Authentic Viennese flair: yes but there are better options.
-Dining: Silvio Nickol is the best restaurant in the city.
-Summary: Nice hotel, but I'd rather eat there than stay there.
Sacher:
-5 star accommodation: wonderful historic building with the best location in the city (in the middle of everything).
-Service: great.
-Authentic Viennese flair: You can't get more Viennese than the Sacher.
-Dining: very good and authentic dining experience and of course there's the
Sachertorte.
-Summary: Perfect balance between historical (
Jugendstil) and contemporary (Pierre-Yves Rochon) style.
And the winner is...
-5 star accommodation: Sacher
-Service: Sacher
-Authentic Viennese flair: Sacher
-Dining: Palais Coburg
In a nutshell, stay at the Imperial or the Sacher, dine at Palais Coburg (Silvio Nickol), have a drink at the Park Hyatt (The Bank) and have a piece of
Sachertorte at the Sacher (Café Sacher)... and of course don't forget to eat a piece of
Annatorte &
Apfelstrudel at Demel