Yes, your activities look quite reasonable: Central Park, major museums, Rockefeller Center / The Empire State Building, etc. These are major icons and they'll definitely give you a good slice of the New York experience.

Museum-wise, The Metropolitan Museum of Art ("The Met") is New York's top, premiere museum. It's a fabulous place and some parts of the building are almost as captivating as the collection itself (the strangely overlooked rooftop garden is incredible, but it's unfortunately closed when you're visiting). You might also consider The Museum of Modern Art (MoMA), another major institution right in Midtown.

Some other options to consider:

• The Circle Line: They offer various boat tours around Manhattan. It's a unique and unbeatable way to watch New York's skyline go by (especially the evening cruises). The boats include indoors spaces, so you don't have to worry about being too cold.
• The Brooklyn Bridge: Walking the Brooklyn Bridge is a classic experience and offers phenomenal vies of lower Manhattan. I do recommend it if you find the time. You can also explore some really interesting areas in Brooklyn once you reach the shore (DUMBO, Fulton Ferry Landing, Brooklyn Heights, etc).
• The Roosevelt Island Tramway: This is basically a gondola for commuters. Give it a round-trip ride and you literally fly over midtown Manhattan. At $2.25 a ticket, this is an excellent deal for a really unique experience.

And for holiday-specific ideas:

• Holiday window displays. These are always elaborate, creative and draw big crowds. The big ones are up on 5th Avenue (between 50th & 59th St), at Lord & Taylor (5th Ave & 38th St), and at Macy's (6th Ave & 34th St, i.e. "Herald Square"). You can easily walk between all of them in about an hour.
• Ice skating. The Rockefeller Center rink is the most famous (and crowded). Wollmon Rink is in a gorgeous Central Park setting (with great city views). The Pond at Bryant Park is especially picturesque in a small park in the heart of the city, and it's free!.
• The Holiday Shops at Bryant Park is a seasonal shopping village offering everything from Tibetan trinkets to gourmet waffles.
• Central Park. I know it's already on your list, but if you're lucky, a snow-covered Central Park is absolutely beautiful. So hope for snow!

There is, but it closes up shop just before you arrive. So you're going to miss it. However, there is the Union Square Greenmarket. It's a great event where local farmers set up shop with fresh produce, artisanal meats and cheeses, baked goods, etc. There's also a mix of artist booths.

It's practically outside your hotel door, so definitely check it out and pick up a snack. You can catch it Monday Dec. 28th and Wednesday Dec. 30th (daytime).

The Union Square Greenmarket? Done.

Sure. I shifted the Roosevelt Island Tram from Tuesday to Wednesday. Since it's in Midtown, it's not so convenient from the Statue of Liberty. Better to visit it when you're already in Midtown.

Otherwise, things are looking good!