I think you should probably cut one of the museums. Last year (or maybe two years ago?) I tried to go to the MoMA around Christmas/New Years and the line to get in was literally hours long. So I would be cautious about that if you're planning to go on a day that a lot of people won't be working. You shouldn't have any trouble getting to see Nintendo World or the Highline (which is awesome). When I lived in NYC a few years ago, I spent an entire day at the Met a few times and still didn't think that I had seen everything. Can't say how crowded it will be around the holidays, but it's a huge museum and has a little bit of everything in it, including a modern art wing.