Best way to spend the afternoon in the city with kids?
Because I love a mix of urban and green, I have two favorite city itineraries, which are dependent on family mojo, mood, and money. One is the classic Boston Common/Public Garden experience; the beauty of this space never escapes me and it's wonderful to have the playground and spray pond/ice skating rink there for the kids. If you're picky about organic foods like I am, I recommend packing a picnic lunch.
If you don't mind spending some money and have a little more energy in the tank, I love the waterfront area where you can enjoy Christopher Columbus Park, the Rose Fitzgerald Kennedy Greenway (pictured), the Aquarium, the North End, and/or Faneuil Hall. You can even enjoy an elegant lunch with the kids (yes, there's a kids menu) at Sel de la Terre.