As a New Yorker, I don't think you'll have problems unless you're blocking traffic or people are tripping over your tripod. Certainly you don't want people tripping over your tripod in the subway! I've seen tripods on 5th and 42nd Street and no one bothered the photographer.

You'll be close to the iconic Flatiron Building on 23rd Street and 5th Avenue. http://www.flickr.com/photos/alankle...57625796644064 (Sorry it's digital but I was on my way to work and that's all I had.)