Staten Island is used to having the watered-down version of everything cultural - we have nice little museums, but they cant compete with Manhattan...we have a cute little kids zoo, but it's no Bronx Zoo...we have galleries, but...
However, the Staten Island Botonical Gardens are as good (if not as large) and very different from the cities other gardens. First of all, for kids, the Secret Garden is a fantasy castle and garden perfect for any child obsessed with robin hood or king arthur...and besides the beautiful more typical flower gardens, the Chinese Scholar's Garden is unique in the city. It is peaceful and a gorgeous example of this living Eastern art form.
The only bad thing about the gardens is you'll wish you could enjoy them all year, instead of just the warm season.