We just got back from NYC about a month and I'm definitely going back!
We were there for 3 days, but I think 5 days should be enough.
Get the 3+ day NewYorkPass, it will save you a lot of money!
http://www.newyorkpass.com/
Also, buy your NYC T-shirt ( 5 for 10.99) at Times SQ.
Around Empire State building, they have a lot of cheap NYc sounviers.
Hotel wise, book early. We stayed in Chinatown (Hotel 91) but it's clean and fairly cheap- though you can heard the subway at night, it didn;t bother us. Becareful of big and cheap hotel, I heard it's not clean,, The last thing you want is to bring home some bed bugs.
Broadway Show: If Wicked was too expensive ( it was for us), so we went to see 'Fuerza Bruta", we got a coupon online and pay half price =) so check online! .. Let put it this way, we will never forget this show.. we had a blast!
http://www.broadwaybox.com/ ß for cheap shows!