I am a US citizen living in Vienna and working for a local company. This is my first post on CH. I felt guilty always looking at posts but never contributing. I hope this offers some small help to people seeking casual mid-priced good places to eat in Vienna.
This is not comprehensive or inclusive of fine dining. I am married with no children and eat out frequently.
Note--Many Vienna restaurants prefer reservations for even casual places for both dinner and sometimes lunch. You do really need to call ahead for many popular places.
My #1 tip: Check out a blog (still live but discontinued) called sushiandstreudel.com . It was written by a foodie American married to an Austrian and living in Vienna. She offers a very good list of casual places and they are all good. Pick one and you basically can't go wrong.
1.) Try a Beisel--the Austrian version of a small local bistro. My favorite in the inner city is Gasthaus Poschl. Rudi's Beisel is just outside the main inner city but excellent. (both need reservations)
Favorite Asian: Liounge, Pho Saigon (near Cafe Schwarzenberg), On Market, Bangkok Thai (near Kettenbrukengasse ubahn), Sapa Experience, Shanghai Tan
People Watching: Drink outside in summer at Naschmarket. Mostly avoid the food and expect tourist crowds, but good for drink and people watching on Saturday morning--if you can get a table.
Spanish: Bodega on Parisergasse
Greek: Ellas on Judenplatz (expensive but good)
Turkish: Restaurant Kent and you must try a Doner Kebap at a food stand--delicous! The one outside Kagran mall is my favorite or Schwedenplatz.
Fench: Le Bol (lunch/breakfast), Cafe Francais (lunch/dinner), Beaulieu (lunch)
Austrian: Try a Beisel as above, but I have to admit I always enjoy Tafelspitz at Plachutta. Touristy and expensive, but food is always good. Note that the Plachutta by Opera house specializes more in Schitzel and the Plachutta by Wollzeile specializes in Tafelspitz (and with better side dishes--I prefer it).
Beer Hall: Wieden Brau or Schweitzerhaus (in Prater--best beer garden) in summer. Some people like 1516 but its owned by US brewing company and not as many local beers. I like Wieden Brau better. Beerklink has fresh Austrian Gooser beer on tap and is quick easy choice.
Coffee House: Many lists available online---Just note that there are different styles and atmospheres. Cafe Central is good to see one time, but it is a crowded tourst place. Try others to get more authentic experience.
USA style food: Livingstone or 1516
Favorite cocktail bar: Krugers American Bar or Puff
Hope this offer some quick help--many other great places so check them out and have fun. Enjoy Vienna!