Have you checked Sensorly? Work in New York has already started.
Granted, most of the city still isn't covered, but it's a start, and you have to remember that work slowed down in the region because of Sandy. Yeah, it was a long time ago, but it still takes time to repair it and catch up with Network Vision.
Just because Sprint hasn't mentioned a city in its announcements doesn't mean LTE is completely unavailable. It just means they don't have what they consider adequate coverage yet.
If it isn't in your area yet, you may want to wait to upgrade to an LTE device, but Network Vision progress will probably speed up sooner rather than later, barring any terrible weather New York may experience this winter. Expect much improved LTE coverage in the coming months.