Let me know if you want any info GC.
Do as much as you can and take some comfortable walking shoes. I walked my feet off, that and the tour bus is the only way to see it all. Times Square stays open til gone midnight so do that at night if there are things you want to see during the day. And set your alarm in the morning as well, you will regret sleeping in.
One of the tour buses does a night time loop, this will take you downtown to brooklyn or uptown to harlem depending which way you want to go. And because its night, its really pretty.
Oh and its safe there. I never felt scared at anytime. The city never sleeps so there are always loads of people around.
I could go on for ages, but I don't want to bore everyone.