What about beginning (taking-over) service on (Amtrak's, which operated for a period of time) Atlantic City line?
Good question.
Some of NJ TRANSIT's first official acts were the abandonment of several rail lines. By 1983, the NJDOT/NJT duo had succeeded in wiping out the West Trenton Line (which at one point brought SEPTA trains through New Jersey to Bound Brook, then over the Raritan Valley Line (RVL) route into Newark. In later years, it was a separate train requiring a transfer in West Trenton), the old Atlantic City Line (exclusively east of Lindenwold, and it also had branches to Ocean City and Cape May), service beyond High Bridge to Phillipsburg on the RVL, and the remnants of service on the old Central RR of NJ -- a shuttle train connecting the RVL at Cranford with Elizabeth (downstairs from the NEC line station) and over a bridge into Bayonne.
These are all decisions which have been second-guessed in recent years. Bayonne service is impossible because the lift bridge over Newark Bay is out. There is a seasonal tourist type operation called Cape May Seashore Lines which runs the Cape May service, but only within Cape May County. There are talks of one day extending it to Winslow Junction so it can connect with the existing NJ TRANSIT Atlantic City Line. As population moves westward in NJ and even with some New York City-area commuters now living in Pennsylvania, the re-extension of the RVL back to Phillipsburg and possibly into Pennsylvania's Lehigh Valley has a lot more merit than it did 20 years ago.
NJ TRANSIT has studies on its website about re-activating the West Trenton Line, since population and business have soared in the Route 1 Corridor. What had been perceived a self-competition (the thought was that stations in places like Pennington and Hopewell would take commuters away from Princeton Junction and other NEC stations) is now a larger necessity since the NEC stations, trains, and parking are all at capacity.
Which brings us to your question, the Atlantic City Line (ACL). Amtrak wanted to get into this business, and in fact they led the project to restore the line for service. Residents of the towns along which the trains would pass complained that this so-called "Gamblers Express" would make noise, cause delays and danger at grade crossings, but not serve them. NJ TRANSIT entered the fray, promising to provide local service to those residents so that they could take the train to gamble as well. Amtrak began its service in the early part of 1989, providing service mainly to points along the NEC as far north as Springfield and as far south as Richmond. They later converted one of the Harrisburg-Philadelphia Keystone round trips into a through Harrisburg-Philadelphia-Atlantic City train. They also provided, at the time, the only service from 30th Street Station in Philadelphia to Atlantic City. NJ TRANSIT began in September of the same year (1989) and appeased the locals along the way; although at the start they did not operate west of Lindenwold.
But neither railroad prospered from the service, particularly because they were in competition with each other (particularly PHL-ACY) and with the casino buses. The latter were offering all types of incentives to their customers, while the rail lines either did not, or were in cahoots with one particular casino that some passengers did not want to patronize.
Both carriers had plenty of empty seats, and had to find ways to fill them. The Cherry Hill station was added later, and both carriers stopped there, figuring on business from the now-defunct horse track there. Amtrak went into a short-lived code share arrangement with Midway Airlines, and extended some of their trains beyond 30th Street Station over SEPTA R1 trackage into Philadelphia International Airport. Amtrak was the connecting "flight" from Philadelphia to Atlantic City. I think the airline died before Amtrak's Atlantic City Line service did.
In the end, there was not enough business for two railroads in town, and by the spring of 1992 Amtrak had pulled out of Atlantic City, leaving just NJ TRANSIT as the sole operator. At the same time, NJT began operating all of its trains into Philadelphia. They entered into a Thruway-type of arrangement with Amtrak that still exists today -- you can book an Amtrak trip through to NJT Atlantic City Line points and get your tickets from Amtrak.
NJT still does not do splendid business on the ACL, but when there are conventions in town (the new convention center is in the same building as the rail station), they do fill up the trains. Much of the business is casino employees, who work all types of odd shifts and require almost 24-hour service. Interestingly, there is almost no Philadelphia market on this train -- most of the ridership is oriented to Atlantic City. Commuters to PHL prefer the PATCO high-speed line and the more direct bus service.