Most hotels have Wi-Fi access, often free of charge. But if the hotel does not have free internet, don’t worry, because Wi-Fi coverage is available almost everywhere, in cafes, parks and at the libraries.
You can use pre-paid data plans from local mobile operators, for example:
http://www.att.com/shop/wireless/plans/prepaidplans.html (If you need a zip code, enter hotel’s zip, or just 10001).
If you need to connect your tablet, for example, an iPad, to internet in New York, outside of the wi-fi zone, you can purchase a data pass, an alternative to a sim card for tablets.
Here are the options: https://buyasession.att.com/sbd/Common/ShopRatePlans.action.
Please read instructions carefully when you sign up, as some plans get auto-extended and you need to unsubscribe from the service when you don’t need it any longer. Otherwise mobile operator will continue charging your card.