Well I originally suggested Liberty Science Center for the kids, but I may have an alternative if you want to go to NYC.

Take a taxi to Exchange Place in NJ, and take a ferry to Battery Park City in NYC, which is by the river and close to the new World Trade Center and 9/11/ museum and other things. http://www.nywaterway.com/PaulusHookTerminal.aspx

The thing you need to figure out beforehand is if it will be open on Dec 26th as its a Monday but the day after Christmas so it may be on a weekend schedule, in which case it does not run. But if that runs, it could be a fun option.