Oh Boy… don’t get me started. Lived in Manhattan for 6 years 
Going back in a few weeks on business - hopefully, get the chance to catch up with the bartenders & places.
A truly amazing place.
What would I recommend? - too much to go over.
ESB and Top-of-the-Rock are fantastic in good weather.
Walking around Grand Central station - get the photo of the central clock!
Walking down Broadway (heading south) from the bottom-left corner of Central Park - you’ll see a huge number of neighbourhood changes.
Cycling in Central Park followed by drinks at the boating lake bar/restaurant.
Rollerblading/walking down the west side highway by the side of the Hudson.
The Intrepid museum is amazing if you are into that sort of stuff.
A helicopter ride can be great (weather depending) and a hop-on-hop-off bus ticket can get you around easier than trying public buses/subway if you’re not familiar with them - plus you’ll see more!
230 fifth (rooftop bar and inside bar just below if the weather is bad)
Any restaurant in ‘the village’ (Lupa especially, but make a reservation waaaayyy in advance!)
Renting a car, driving north through upstate NY and walking around the surrounding area of the amazing Mohonk Mountain House hotel - the scenery is unbelievable and exactly the opposite to NYC!
I’ll stop there… 