has anyone stayed at the Mercure wien city hotel in Vienna (or any Mercure hotels there)? How was it for location (sightseeing), comfort, value?

Hi
I understand your question now. In the future can you be more specific?
It's like asking "Holiday Inn" Mercure is a large hotel chain with hotels around the world.

Which Mercure do you specifically mean? There are several. I stayed at one and was not particularly impressed. My room was stuffy, decor sightly tired, not air conditioned and the neighborhood was not particularly interesting. However, there is a lot of variability in Mercure properties even in Vienna (unlike the Novotels or Ibis hotels, which are known for their uniform style).
If you want to stay in an Accor property, consider Priceline for 4-stars in central Vienna--the Sofitel is one of the most commonly used properties in that category. Or check the Accor web site...with their Internet specials, you could get the Sofitel for the same price as the Mercure.

The Sofitel Vienna is an excellent hotel in a good location. A bus stops across the street. Check the accor website for potential deals for your travel dates or try priceline.

We stayed at the Mercure Wien City in March 2004. (The Mercure Wien City is the name of a specific Mercure hotel in Vienna; there are five or six in the center and one is even just a couple of hundred yards away.) The location is excellent, only about three blocks from the Stephansdom. The rooms are relatively small, but otherwise it is a typical Mercure. At the time we stayed last March, we got the room through the www.raileurope.com site at a price that was lower than the other hotel places (about 80 dollars a night that included two full buffet breakfasts each day), but I haven't seen a price like that on their site since then. I have heard of people getting this Mercure through Priceline for about 45-50 euros without breakfast, but I'm not a Priceline person so I'm no help there.