I prefer a bistecca fiorentina in the Cantinetta Antinori or at Da Moritz, if you prefer steak American style there is also Frank´s and the Steakpoint.
(all in the inner city, contact details at http://www.falter.at/web/wwei/home.php
The Falter lists 94 restaurants with Thai food...
My favorites are Thai Isaan Kitchen on Gumpendorferstrasse and Damoa behind the Vienna Hilton.
If you have money to spend you might try the Patara, the Indochine or Yohm, but we consider these as a waste of money.