I feel you can learn everywhere . But I felt my kids learned a lot about oceans / sea animals / tide pools etc. on our trip to Acadia, ME this summer. And they learned a lot on our spring break trip to Italy last year. For both I got some kids books on the area before we left.

We have done some school study tie-ins local to the Commonwealth: Civil War heritage sites like Antietam, Appomattox, Manassas, Leesburg, Warrenton, Lexington
War of 1812: Tudor Place in Georgetown, Baltimore
Revolutionary War: Yorktown, Williamsburg. Can also do a marine science tie-in with visiting VIMS across the bridge from Yorktown. Jamestown deserves its own trip.
Boston, Charleston (SC), Savannah, Philadelphia, NYC all on our list over the next few years.
Countless FREE museums in the DC area make me feel grateful to live here. Chicago museums are wonderful but can be so expensive esp. Science & Industry. The Henry Ford in Dearborn (MI) is wonderful but also $.

Some great Children's Museums--

Houston
Baltimore
Chicago (and Chicago has a lot of educational and fun stuff and feels just enough different from DC to feel cool!)
San Fran (the Exploratorium)

My kids have also enjoyed factory tours like Utz, Jelly Belly..

Most overlooked educational activities might be the Presidential Libraries so far my favorite is the Reagan Library. I think my kids would vote for the Jimmy Carter one.

A more local gem is Frontier Culture Museum in Staunton (also plenty of caverns and such on the way to/from)

New York - Ellis Island, Tenement Museum, Museum of Natural History, Metropolitan Museum of Art, 911 Memorial, Museum of the City of New York, Stock Exchange, Math Museum, and many wonderful free walking tours.

London area - Tower of London, Bank of England Museum, Science Museum, National Portrait Gallery, British Museum, Greenwich, Hampton Court, and so much more.

For natural history/science, Yellowstone was amazingly educational for our kids this past summer. (They love Williamsburg too, but that's a different kind of education!)

Annapolis
Baltimore, Boston
Charleston

Mount Vernon, Monticello

The Caribbean

Costa Rica

Everywhere in Europe

Every trip is educational.

Charleston

What age are the kids?

Kids can learn things anywhere that is a real place where people live or have lived for a reason other than tourism.

Hawaii
Boston- Freedom Trail, Concord, Old Sturbridge Village
Philadelphia- Penn Museum, academy of Science, Franklin Institute, Independence Hall. Add in Valley Forge
New Mexico- Santa Fe, Navajo culture, Puebloan culture and cliff dwellings, Georgia O'Keefe museum, Chaco Canyon, Rte 66,

Newport, New Orleans, Chicago, anywhere on the east coast.

Philadelphia, Boston, Gettysburg, etc. the east coast is full of areas like Williamsburg.

We try to do at least one “educational” trip each year... in addition to fun trips. We do some fun things to... but the educational component is the main goal. For instance, Williamsburg is perfect. History of Williamsburg, Jamestown, and Yorktown- plus a fun day at Bush Gardens.

Anyone have another great idea- any age?