$300.00 is fine. Bring credit cards and ATM cards and if you need more you can get it.I am going to post links to several articles about what to see in New York at Christmas, How to Use the Trains and the cheapest times for Museums. Be sure to read to the end, because links to various websites are listed there that will be helpful too:http://www.associatedcontent.com/article��http://www.associatedcontent.com/article��http://www.associatedcontent.com/article��
How long you re staying in the city? If you re staying 2 or 3 day, some thing in the neighborhood of $500 will do. Any day beyond that will cost you. Just make sure, you spend it wisely.Good luck