If you want to stay close to the action have a look at Radio City Apartments which are a stones throw from Radio City Musical Hall.
We booked them in June this year for our 10 night holiday in February 2014. We have been planning our trip for a while and had intended to stay in a standard room, but by booking so far in advance, we were able to get the penthouse for $600 less than what a standard room would have been had we booked it latter on.
We booked it on the recommendation of family who stays there every year and love it because it has a kitchen and more space than your average hotel room. We like the idea of being able to buy breakfast stuff and leave it at the hotel so we can splurge on other meals and also of there being a laundry.
If you don't mind staying a little further afield have a look at Long Island City, there are a lot of posts on here about the best two or three places to stay.
Finally, that's a long time to stay and I'm sure many places would be glad to know that they have a room booked for that long. I would not hesitate to find a couple of places and then email them and ask what they will do for your business.