|Stuttgart Opera House -ballet is the pot of gold at the end of the rainbow|
Another longtime fave of mine is the City Hotel, Uhlandstraße 18, rooms starting at 79 euros including a great buffet breakfast. It is only 9 minutes walk from the theatre, not quite as convenient for the main shopping streets and train station (both still walkable) or airport as the Astoria, but as Stuttgart has a fantastic public transit system it is definitely not difficult to get where you're going.
There is a good Italian restaurant, La Piazza, just down Uhlandstrasse from the hotel, on the corner of Urbanstrasse.
Make sure you stop in for Kaffee and Kuchen at the Grand Cafe Planie (the big yellow building on one corner of Charlottenplatz). Their cakes are fantastic!