or go to the observation deck on the Rockefeller building and you will be able to actually see the Empire State Building too
New York is awesome in any case, I'm sure you'll have a great time. And as Stimpee said, no visit to NYC is complete without meeting the legendary mr J. Roth
I made a little blog during me and Stimpee's stay in NY back in '07 which you can still find here:
http://snakedogman.vox.com/
maybe it will give some inspiration for things to do