The virgin hotel is a great location OP!
We stayed literally a minute away from it recently, there's two subway stations really close so you can quickly hop up to Central Park / down to Brooklyn and it's really easy.
You've also got an Essa Bagel / Starbucks a minute or two away for a quick breakfast, only a 10 min max walk to flatiron and all the great bits there, similarly only 10 min max up to Macy's and broadway / bit further for Times Square. We love the location and stay in that area because it's such a good place for everything we need!
Definitely recommend the Highline, although it won't be in full bloom because of the time of year. We enjoy NYC more in the colder months too, it's just lovely and fresh.
We love Central Park, if you get the tube up to the bottom left corner of it there's a Starbucks to grab a coffee to keep you warm as you wander around, it's beautiful. If you do a small loop around the lower half (going across sheep's meadow) you can come out at the top of 5th ave then walk down for some shopping.
Definitely recommend top of the rock, because you can see Central Park but also the empire state! The Empire State Building is great too but we preferred TOTR just for the dual aspect. The Edge was good as well but the views (for us) less impressive.
Chelsea market is a must for a great lunch - there's so much good food (definitely recommend the tacos from Los Tacos No1, the pizza and the noodle bowls!).
The tub was fab for us, you can tap in / tap out or get a weekly card and we used it multiple times a day to get everywhere, it was fantastic. We still hit over 20k steps most days but they were steps exploring rather than just trudging from one end to the other!