I have a tip for you, if you ever visit Vienna, get a 24(48,72)hr unlimited ticket and spend some time on the subway (U-Bahn) with your kids, riding the various lines. The entire subway system has different trains (some more like street cars, some more like urban rail) and tracks run in underground tunnels, shallow trenches and over open ground.
Honestly, one of my favourite aspects of traveling is simply using the local mass transit.
Coming from a city where it's a particularly bad joke, it's still a novelty, and it provides such a different perspective on the city than "where can I park within orbit of $specific_destination"
