Советую не останавливаться в chain hotel, а снять квартиру. Утром кофе с плюшками, день по эксурсиям, продукты на рынках, ужин дома, погрузитесь в образ жизни.
PS Вообще август - не очень хорошее время. Жарко и толпы туристов. Очень советую сентябрь.
PPS Мой список приезжающим в Вену:
Belvedere (palace, gardens and art museum)
https://www.belvedere.at/
KHM (classical art)
https://www.khm.at/en/
Leopold (history of Vienna in 20th century)
https://www.leopoldmuseum.org/en
Museum Hundertwasser
https://www.kunsthauswien.com/en/
Albertina ("modern" art museum: Monet, Picasso, Chagal, etc)
https://www.albertina.at/en/
Schoenbrunn (palace, gardens, strudel baking classes)
https://www.schoenbrunn.at/
Time Travel (immersive experience, overview of the history of Vienna, cool for kids)
https://www.timetravel-vienna.at/en/
Prater Park (amusement park, park with alleys for running and biking)
https://www.praterwien.com/startseite
Oper (performances and tours):
https://www.wiener-staatsoper.at/
Stephansdom(cathedral, tours, climb up the towers, concerts)
https://www.stephanskirche.at/
Peterskirche (free organ concerts every day at 3 pm)
https://www.peterskirche.at/
Restaurant 57 and the view from the bar
https://www.fiftysevenrestaurant.at/
Klosterneuburg Abbey (abbey, museum, concerts, wine cellars)
https://www.stift-klosterneuburg.at/en/
Walk around vineyards in Nussdorf:
https://www.weinwandern.at/grinzing-nussdorf/
Linz Tiergarten and Hermesvilla (park, forest, villa)
https://www.lainzer-tiergarten.at/hermesvilla.html
Donauinsel (island with no cars, biking, running, swimming, subs, kayaking)
https://www.wien.gv.at/umwelt/gewaesser/donauinsel/