I’m just getting home from there. Intrepid is a must, and vets get in for free. Must have some form of proof you served. I have a photo of my DD214. The Beretta Gallery is great if you like their shotguns and accoutrements. To many places to eat at. Have fun, but it’s insanely crowded.

St Paul's Church.

George Washington attended regularly and it has incredible ties to 9/11. The fact that it is still standing, much less undamaged as a result of the attack is amazing.

Many good suggestions so far.
1) transportation- not an issue. It’s an island- Uptown is higher street numbers(125th st) vs downtown (city hall). Get the Citymapper app. Use it- enjoy the city.
2) entertainment- it’s there, Broadway, rooftop bars, every museum except firearms.
3) food- NY steak house. It’s a must.
4) WiFi - there are Starbucks on every block