There is precisely one place in the Stephansdom where you can get good pictures. You are not allowed to use a tripod inside the cathedral, so you have to walk up to the iron gate that divides the "tourist area" (for want of a better name) from the benches. In the center is a column that can be used to rest the camera for those 0.5 second exposures that are needed. A warning, though: monopolizing that position for half an hour is likely to anger other tourists and perhaps God himself.
But you get some neat images out of it. Center is exposed at 1/2 second, edges at 1/30, with exposure inbetween being, well, inbetween. ISO 50 for the center and ISO 100 for everything else.
And more photo editing than I ever imagined it would take...