If you follow I-95 northbound, you will be able to drive from WDW to NYC in about 18-20 hours. The interstate takes you close to the coast, but not close enough to be at the ocean. That's how we drive back and forth to WDW.
I would advise spending some time in Washington DC. There is a lot of history there and many of the sites and museums are free to tour. Also, you can hit Colonial Williamsburg, Busch Gardens, Virginia Beach. Another place you can spend some time is in NYC itself. So much to see and do here! (and I'm not saying that because I live in the NYC area). Honestly, I'm not sure there would be too much of interest in many of the states you'll drive through (Georgia, the Carolinas, Maryland, Delaware, New Jersey), aside from making sure you get some good southern food while you're there. Personally, I think you're best off using 4-5 days in Washington DC and another 4-5 days for New York City and the rest of the time you'll be driving.