Welcome aboard the RoadTrip America Forums!
With such a bare bones description of your trip, about all we can offer is some generalities, but they should help get you started. With two weeks (more or less, depending on how long you have to spend in Louisville and Little Rock) you can make this a quite relaxed trip, taking the time to see a number of sights along the way. As a general route, I'd suggest that you leave New York on I-78 west to Harrisburg,PA then take I-81 south and I-64 west from Lexington, VA to Louisville. Highlights of this leg would include the Shenandoah Valley, Blue Ridge Mountains and the Blue Grass region of Kentucky.
The next stretch would take you down I-65 to Nashville and then west on I-40 to Little Rock with possible stops at Mammoth Cave and to enjoy the music and night life of Nashville and Memphis. Finally, I-40 west would take you through the Ozarks and cowboy and Indian country into the desert southwest and Petroglyph National Monument, Petrified Forest National Park, and within easy detour distance of both the Grand Canyon and Las Vegas, before ending up in Los Angeles.
Before we can offer you any more specific advice, we'd have to know what it is you want out of your trip and what your interests are. For basic planning help, start by checking out the RoadTrip Planning pages available at the click of the button above.
AZBuck