One of the best vacations I ever took was a New England road trip. It was a very long time ago, so I don't remember all of the towns, but here are some highlights.
New York City, NY - They have the theatre district and you can take a boat to both Ellis Island and the Statue of Liberty. The line for the boat is very long though, so be sure to purchase tickets ahead of time (either online or at the stand) to expedite the security process. If you're a sports fan, you can catch a game, too.
Philadelphia, PA - A lot of history locations here. There is also a duck tour (which is riding a boat on land and a bit of water with a fun tour guide) and horse and carriage rides on cobblestone streets.
Baltimore, MD - I'm a sucker for piers personally, but Baltimore has a great one! (As does San Francisco if you were looking to go west eventually). However, if you are not one for a pier or scenery in general, I would not go here. Despite all of the research I did prior to our Baltimore trip, all of the "attractions" I found were actually lies. Either the location was non-existent or something that was supposed to be great was an empty shed with nobody around (literally.) Hopefully you can find someone from there to tell you truly what to see.
Mount Vernon, VA - Another history location, but the tours are great! We did the National Treasure 2 Tour, as the site was used as a location in the movie, and that is the only tour (according to our guide) where you get to go underground in the wine cellar. It is also a very beautiful nature location and next to the home is a small recreation of a town from that era.
Washington D.C., VA - One of those "must see" locations. Be sure to look at the area's calendar and either avoid event days to hopefully lessen the traffic, or go on an event day you like - depending on which scenario you prefer.
I'd also definitely look at Boston, MA. Especially the Salem Witch Trial locations and museums. There was also a spider farm we went to where they have small pieces of wood with a spider web plastered on them. We each bought one and have it to this day.
Overall, you may want a driving buddy or two that you can switch between because there will be a lot of traffic. Or perhaps you would prefer to go by bus (so you don't have to drive) or train (more expensive, but traffic is not an issue.) I'd also suggest (if you're willing) to not book hotels ahead of time, but as you go, because you never know when you'll be too tired to drive.