I always try to find spots on foot, because you can get into areas and search around better that way.
Downtown areas are the best. Often offices or other buildings will try to design quieter areas inclosed with buildings on all sides. Those spots usually have some fun areas and architecture.
If you are in smaller cities or towns, it will be a little more tough. Like everyone else said: schools, parks, etc.
If there are any nature trails or other natural parks with trees, boulders, or cliffs, those can be excellent. One of my favorite areas is not even in the city, but out in nature.