The thing I miss most often about living in Vienna is the constant availability of the masses, in Calgary you have to wait for festivals to go to big crowds. Due to Vienna's comparatively mild winters you can even find crowds in the old inner city in that season.
It feels good to get lost in the crowds and just be a part of humanity in such an obvious manner.
There is also the market and food culture. Though Calgary isn't entirely lacking in this area, it is not quite the same.
It's weird to be a market snob, since the elite would never bother with the marketplace. :D
There are other things I miss, but I am not sure that would be so interesting to list.
The thing I would miss the most about Calgary at this point though is my family/social life.