Being a Sparta resident I may be a little biased, however, Sparta truly is conveniently located for travel into the city. Whether via public transportation or driving in, there are many routes you can take. Lakeland Bus has a run from Main Street in Sparta to NYC and you can check out their schedule and arrival times at http://www.lakelandbus.com/Sched80MFE.html.
NJ Transit runs a train line with Park & Rides nearby. You can see their schedules and locations at http://www.njtransit.com/sf/sf_servlet.srv?hdnPageAction=Tri
The Mt. Arlington, Netcong or Dover Stations would be closest to Sparta. However, my favorite way in is 80 to the GWB to the Henry Hudson, cutting through Central Park gets me right where I want to be on the East side.