As a DC kid, I always enjoyed the U.S. Navy Museum in the Navy Yard more than Smithsonian museums. Is it still off the beaten path? |
I second the Philadelphia Museum of Art and Mutter. If you like ships, Independence Seaport Museum, also in Philly, was a blast for me! Got to walk around an actual submarine, so cool!
It's super out of the way but the Maine Mineral and Gem Museum in Bethel was a really cool find! It's quite small but it was super cool. Portland Museum of Art (Maine) was also a lot of fun! |
This is not going to be relevant to OP, but the Indianapolis Children's Museum is by far the best Children's Museum I've seen. I went as a child and still remember it. I don't live anywhere near Indiana, but I'm trying to plan a trip there for my own kids. |
I LOVE the Isabella Stewart Gardner museum. |
The MoPOP (Museum of Pop Culture) in Seattle.
The Rock'n'Roll Hall of Fame in Cleveland. |
The Palomar Mountain Observatory in CA is great if you like star-gazing. Ditto for the Griffith Observatory. |