Nothing really to see at ground zero I felt it wasted a morning ,however a quick look indie the church nearby was worth it and then onto the small pub where the firefighters pictures are shown behind the bar ,great little NYC down to earth bar , very sad feelings in both, it will upset you, depends what you after , hence me having a few beers after in the pub that lost so many , glad we have moved on since that tragedy.
Nice cheapy about 4ish take the Staten Island free ferry over to the island with the workers going home after work , then come back as the sun is going down over NYC , don't take the paid for ones .
Around Times square there is a massive Marriott go up to the top of it ,you have to change lifts, go the top bar which rotates around the city every 45 minutes .
If your into music go to the Bowery
http://www.boweryballroom.com/