I don't have kids of my own but when we're babysitting my girlfriend's young neices, taking them around the city has always been pretty painless. I think it's like most Mediterranean cities in this respect, and children are catered for everywhere (numerous playgrounds dotted all around, the cafe's and restaurants are all child-friendly, public transport has plenty of space for buggies etc.). The ages of your children might make a difference to how easy it would be and I guess also the kinds of things you plan on doing while over there.