Depends on how good a talker / listener you are. Can you carry off a 4 hour walk in the park and hold up your end of a conversation? Then outdoors is fine, but it needs to be daytime. Bear in mind you are coming up against Chol Hamoed, and the streets will be crawling with people you and she most likely know.
If a nighttime date is more practical, then a lounge / hotel lobby is fine, and can be kept to a 2-3 hour date (another hour or so will be eaten up by driving to and from).
Uh, one question. From you opening post, I took the conclusion that you are from out of town and are just looking for NYC destinations. From this last post, I get the feeling you are just starting the dating process. If so, let me ask the folloing: are you working or at least in college to put you on the path to a job that will help you meet the obligations you will agree to when you hand over the kesubah?