So, was thinking about doing a 7-10 day road trip with my 13yo son this summer. Mix of vehicle camping and hotels.Sometime after mid June up to mid August.

Starting out of Northern Virginia.

Do I go to the northeast, southeast, or midwest?
Theme it like revolutionary war or civil war? Historical sites? WWII Ships? Museums? Theme parts and attractions?
Highways or back roads? Tiny towns or big cities?

Things like:
SE
Cape Canaveral for a launch
Pensacola for museum and Blue Angels practice
Huntsville space museum
Stone Mountain
Talledaga or other speedway for a race
USS North Carolina

NE:
Gettysburg
Liberty Hall
Freedom Trail

MW:
Badlands
Indianapolis motor speedway
Mount Rushmore
Old school state fair and/or 4H

Looking for ideas, routes, hidden gems, things to avoid, etc.

One of my best RT memories with my dad was staying at local hotels/motels.   No chains.  B&B type stuff with neat things, like one place was an old roadhouse/saloon.

I think it was New Mexico where you can view the caldera of a dead volcano just off of the main road.

There's a huge meteor crater in AZ that hit just a few hundred yards from a road.

Lewis and Clark trail would be cool.

Nice! Will look once locations get narrowed down.

Good thing it missed the road.

If you do the SE and hit the Cape for a launch, in addition to the Space Center stuff there is a nice little aviation museum in Titusville that's worth a look.
https://www.valiantaircommand.com/

If you stopped for the night in Daytona you could see the track/museum they have, it's a half day experience, drive the hour to Titusville see that museum then check into your hotel. Go to the Space Center the next day, it's an all day thing.

If you are going to Pensacola, the Air Force Ordnance museum is at Eglin, and the USS Alabama is just a bit past Pensacola in Mobile.

I've done 5 long road trips with my boy (now 10), and I'm about to embark in anytime one this summer. I go from here to home (Texas) every time, but I take a different route each time, just to keep it fresh and interesting. It doesn't matter which direction you go, because you can find good stuff anywhere.

I'll give some general tips that can help with the concept:
Get a couple of audio books to listen to for the long interstate stretches.
Don't fixate on distance per day; find the things worth seeing along the way and plan the trip around them.
Allow time for diversions.
KOAs are great. The cabins are cheaper than hotels. They're family-friendly, they usually have pools, bikes, trails and various things to do. After long periods in the car, it's nice to get some activity in.
Find the local flavor. Look up restaurants, museums, and attractions that are unique to the area you're staying in. I've gotten some great ideas by posting in the HTF here for the states I'm visiting. The locals will know about cool things that a Google search might not show you.

100% worth a trip there.

[hate on Idi Amin all you want, but this post would make him chuckle]

Sygic Planner is what you need