Then from Wilmington, you'll have to decide whether there is time for the Outer Banks or if you need

My husband and I (from Australia) are planning to drive from Orlando to NYC (to Washington with train to NYC) in April this year. I would be interested in ideas of towns and cities to visit and stay overnight and good/interesting BBs to stay in. Our budget is medium to good!
Between Washington and NYC, I [in a COMPLETELY unbiased opinion ;^) ] suggest you visit Philadelphia. More important historical sites than any other city in the U.S., if not not the Americas. Also great food and a some nice museums. For example, if French Impressionism is an art form you like, note that Philly has more of such paintings than any city except Paris.
You could LEAVE Orlando, see most of the interesting stuff between that city and the Big Apple, ARRIVE in New York two weeks later, world poker tour and not do so in a rush. Extra time would be necessary to visit both Orlando and New York.
Rent another car there and drive west on US 64 until you get on I-40 west. Take the time to see Great Smokey Mountains National Park. Head north on I-75 out of Knoxville Tennessee to visit eastern Kentucky. Go back east through West Virginia and then back to Rocky Mount to turn in the rental car. Take either of the Silver Service trains into Washington DC or on to NYC if you want to see that first.
tomf: As we've explained on other threads where you've posted that sort of advice, foreign visitors who pre-book their cars seldom face any drop off charges. Their brokers usually arrange hire cars w/o any add-ons.
It sounds like tomf would like you to skip the eastern seaboard. If I were driving, I'd make stops in Savannah, Charleston, the Outer Banks of NC and then make my way up to DC and Philly. It's easy to pick up the train in Raleigh world poker tour or DC and move on North to NYC from there.
Agree with recommendations for Savannah, Charleston, Philadelphia (you can take the train from DC, then another train onto NYC). Outer Banks, maybe if you're really interested in seeing a shore area.
Just drive up the coast to at least Wilmington, NC, another city worthy world poker tour of touring. Between Charleston and Wilmington there is also Georgetown for a quick look--Revolutionary War era homes, small and historic.
Then from Wilmington, world poker tour you'll have to decide whether there is time for the Outer Banks or if you need to just head on up the road. At Wilmington you can take I40 east to connect with I95 and the corridor to DC,Philadelphia and NYC.
The must-stopovers are certainly Savannah,Charleston, and Washington, DC. I would say a full day in Savannah, two in Charleston, anything up to five in Washington. Then going on to Philadelphia by train is good advice. Though I am like tomfuller a train fan, I do not recommend it for what you want to do south of Washington. North of Washington, it is the only thing that makes sense.
Monticello, Thomas Jefferson's house near Charlottesville, VA is extremely interesting, and many find Williamsburg and Jamestown, VA to be interesting. The museum at Jamestown is particularly good at showing how the settlement of this part of America came about: hint, not convict ships but pretty much people with no other choice.
You will be following spring northward. Azaleas and other spring flowers will be spectacular until you get to Washington. You may want to begin taking an allergy medicine world poker tour a couple of weeks before your trip begins (the non-drowsy ones take that long to provide protection) because the pollen load is intense. The green powder all over your car will be pine pollen, but believe me everything flowers at once!