Liam,
Been a couple of times. Once with the boys and once with the other half.
Going to a show on broadway is ace. Then walk up to The Stage Deli (quite near to Times Square) for some midnight food!
Top of the Rock is better than Empire state but I did both last time as you kinda have to do empire!
Don't waste your time going on to the island with the statue of liberty. It's better spent in battery park / financial district or the pier areas which are cool.
Walking over Brooklyn bridge is cool. China Town is worth a look as is little Italy. The village is nice and Washington Square has a real buzz about it.
Central park is nice and the hirse drawn carts is a nice way to see it.
Go to Times Square in the evening for the first time. It's like Vegas, looks better at night!
Hmmmmmm, I could go on and on to be honest!