Have you considered the Pellagio? It is made by Vespa. It has a powerful motor and the anti-theft system is really cutting edge.
Thanks for the suggestion! Aren't those scooters though, not bikes? (Unless my Googling needs some practice ) Anything that's not class 1 (pedal assist) is illegal in NYC, so would have to be ridden on the street rather than the protected Greenway that runs along the west side of Manhattan (traffic free, riding through parkland and along the Hudson River). I wouldn't really consider anything that I can't ride on bike paths.