My average is 1.7hrs, done it maybe 20 times now. A fantastic flight, I don't think it is ever possible to get bored of doing it.
You can do it in an hour from FRG off-peak times if you just head straight to Alpine Tower or GWB, fly down to VZ and then do the 500ft over the shoreline under JFK bravo on the way back.
The place to be extra careful is around the Statue of Liberty, where the helicopters do their climbing turns. Apart from that, the traffic even during busy times is very well organized. Learn the reporting points (they are very easy to identify, just remember them) and broadcast on 123.05. Don't bother with your callsigns or anything, the most common way is just a short "Cherokee, VZ, 900, northbound". No need to block up the frequency with "Hudson traffic, Cherokee 1234AB, 900ft, Verrazano Bridge, Northbound, Hudson".