Well, if you're on an alone trip, definately make it the Bronx. But you throw in that you're bringing a 7-year old. The Bronx is quite large and hard to see in one day, because of limited hours and lots of exhibits. Children don't react very well to walking a lot, so if you make it a Bronx visit, be sure to visit those attractions you can't miss (Congo Gorilla Forest, Madagascar!, Tiger Mountain) and throw in a pleaser for the kid, such as the Children's Zoo. A question to anyone who's been to the Philly Zoo, can their zoo overwhelm a child like larger zoos like the Bronx can?