i'm in my twenties, and when I went to NYC, I stayed on West 45th Street. It's right next to Times Square. Can't get more central than that. Was handy for all areas of the city. Have a GREAT time! you'll love it - it's an absolutely amazing place to go. I'm v. jealous!
Try the Waldorf=Astoria. It's very central to everything that you would want, including the cheaper and better bars and restaurants on 2nd Avenue. You will be treated like princesses, and the prices are very reasonable! I'm just back and it was fantastic. Enjoy!