He'll give you a list of sites. I can suggest Fraunce's Tavern down on Pearl and Broad Streets. That's where Washington gave his farewell speech to his officers. There is a museum on the 2nd floor. From there it's a 30 second walk to the Staten Island Ferry. You can ride that for free to Staten Island and back. Nice views.
As for tours, try Big Apple Tours. They are double-decker red buses and you can hop on and off wherever you'd like. They go all over the city.
free? how’s that possible?