I'm a folding bike lover and own a Dahon and Brompton. The Bromptom is the most reliable bike never mind folding bike I've ever had.
Anyway I'm not here to start another folding bike A Vs folding bike B debate lol! I would go with the option of a Swift (available in NYC for sure) or a Bike Friday Tikit. I do not wish to challenge the advice of Snafu21 as the she is a Jack Lockjaw acolyte and I have a Dahon Cadenza 08 and love it. However the Swift and Tikit both have a very fine ride, the robust frame to take your weight and are still relatively compact folders. Added to that they are perfect for the variety of surfaces and distances you require the bike for and both quite fast bikes as you get fitter.