re: Spur of the moment NYC trip w wife and kids

You have lots of great recs already. As far a getting around you can still hail a cab, but services like Uber are very popular. If you are a popular place like the Met, walk a few blocks away before getting a ride. Carefully watch the fares... peak surcharges! Subway is quickest for long hauls like Yankee Stadium...still not the must user friendly experience.