We regularly take did with us on city breaks. She is 11 now and we have brought her to:
Venice
London
Paris
Berlin
Budapest
Palma
Verona
Further afield we have also spent time in Sydney, Brisbane, Bangkok and Toronto with her.
We are heading to Kraków in a couple of weeks and have Florence / Rome / barcelona / Prague in our sights for future trips
I would also love to visit Copenhagen, Stockholm, Vienna and Warsaw in the future
We research the trio well and roughly plan it out so we have some idea what we would like to do each day. That works far better for us when we have dd with us as otherwise hours can just drift away as we debate where to go and what to do.
We have never had any issues finding suitable things of interest for her to do and we try to do a mix of things we like and things she likes.
For instance when we go to Kraków we plan of visit the Schindler factory museum and the salt mines and the large indoor market and a number of cool cafes for cake and hot chocolate etc and she is interested in all of these things at this age
Have fun - city breaks are my favourite type of getaway !!