Welcome to Fodor's! What time of year and for how long will your trip be? And do you have particular interests: art, history, sporting events, more indoors or outdoors, city or not...

Newport, RI is really neat.

We are planning mid July and want to show the girls a little history and educational interests along the way. We plan on going for between 7 and 10 days

In Boston, do the Freedom trail and visit Lexington and Concord (make sure the girls have the background - assuming they have had basic american history by now). A stop in Newport is good to view a few of the cottges of the wealthy and Mystic has a cute aquarium as well as a ship museum (thye might have limited interest).

I would definitelt leave at least 3 days each for NYC and DC since they both have so much that is worthwhile - as well as fun. It's easy to mix some museums with shopping or perhaps a meal at a sidewalk cafe in an area like the WEst Village where they may see "someone".

Here are some places to consider while in transit between cities:

Old Sturbridge Village (central MA), an ``open air museum'' showing life in New England in the 1790's

The Mashantucket Pequot Museum (central CT), a gem of a place depicting the history of native americans in the region, from ice age to current times.

Mystic CT has an open air museum that re-creates a seaport from olden times.

You can drive along the jersey coast (scenic in many spots but avoid it on summer weekends) and take the car ferry from Cape May to Delaware. Then visit Assateague Island.

If you want to stay inland, Philadelphia has that big bell, and other national heritage sites. Baltimore has a great central waterfront area with museums and shops.

Baltimore also has Fort McHenry where Francis Scott Key wrote the Star Spangled Banner. Interesting film and tour of the fort.

Mid-July will be hot and could be very hot. Definitely plan your trip with watering holes - or at least hotel pools - in mind!

From Boston to NYC, you could take the inland route - hitting Lexington, Concord and the Old Sturbridge Village (among others) - or the coastal route, with Newport, RI, the Pequots, Mystic... Plenty of nice beaches from southeastern MA through RI and eastern CT. (There is much less public access to beaches in the CT towns closer to NYC.)

On these boards, I'm always promoting trips from Boston out to Lexington and Concord. But I'd have to say, unless your kids are into colonial American history, those towns' historical sites are not the most fun at that age. You can pick up plenty of Revolutionary War history in Boston itself, much of which is more kid-friendly - the new mobile walking tours of the Freedom Trail and Boston Black History look great.

That said, Concord has more going for it than just Revolutionary War history: the homes of the Alcotts (where Louisa May wrote Little Women), Hawthorne, Emerson, and others are museums run by the local historical society. And nearby Walden Pond - made famous by Thoreau - is now a state park with a swimming beach.
http://en.wikipedia.org/wiki/Concord,_Massachusetts#Points_of_interest
http://www.mass.gov/dcr/parks/walden

> want to show the girls a little history

With this statement from the OP, I am utterly dumbfounded that the only mention of my city is little more than, "Philadelphia has that big bell." Independence Hall happens to be where the Declaration of Independence, the U.S. Constitution, and the Bill of Rights were all composed and adopted. The historical value of the events in that one building exceeds that of the grand total of events in most states!

And if that's not enough, there's also the Rocky Steps!!