Thought I’d share a tip - during summer school holidays in Vienna, school aged children (until 15th birthday) are free on public transportation in the city. This rule applies to all forms of public transportation, including buses, trams, subways and regional trains that are within city limits. The school holidays start tomorrow July 1 and end on September 4.
As visitors hopefully know, the public transportation system in Vienna is excellent, cheap and convenient. Use google maps public transportation mode to determine routings easily. Buy 24-, 48-, 72-, weekly or 7 day passes for the adults. The olname of the public transportation system in Vienna is Wiener Linien. Do not use hop on hop off buses or taxis to get around - that is just silly.
My favorite things to do with my kids - Kahlenberg hike and ropes course, boat rental at Marina Hofbauer for a ride around Alte Donau, DIY scavenger hunt at Kunsthistorisches Museum, Stephansdom Tower, Schonbrunn Maze/Labyrinth, Strandbad Gänsehäufel (a great swimming area), shopping on Vienna's main shopping street Mariahilferstrasse (between the Ring and Westbahn). Links below.
https://www.wien.info/en/livable-vienna/parks-green-spaces/kahlenberg-forest-rope-park-349518
https://www.wien.gv.at/umwelt/wald/freizeit/wandern/wege/wanderweg1.html
https://www.marina-hofbauer.at/
https://www.schoenbrunn.at/en/about-schoenbrunn/the-palace/tour-of-the-palace/maze
https://www.wien.info/en/gaensehaeufel-132638