St. Stephens Cathedral - Vienna - how long to plan to see?

I also have two younger kids. We have visited the cathedral many times.

My suggestion - walk into the cathdral, look at the interior for a couple of minutes, visit the crypt (my kids think this is cool), then take the elevators up to the tower for the view and to see the bell. One hour will cover it. Not exactly the most kid-friendly attraction, in my view. If they are really small, the tower might make you nervous.

The south tower gives you a much better view, but it means climbing approx. 400 steps.

Thank you Emily and wmt1!