Another vote for 395.
Get a very early start to get past the hotter areas before they get crazy. It will get nicer once you get past Olancha. It might be too hot to stop at Manzanar on this trip.
I agree that everyone should visit Manzanar at least once, especially if you have teens.
Keep an eye on your speed. The CHP works hard to keep 395 safe, which means they're very present and actively enforcing speed limits. Set your speed to 59 if you're towing and you'll have a relaxing trip.
One more thought on the heat. If you fill your tires the night before and it's cool out, back off about five PSI to give them some room for expansion in the crazy desert heat the next day.
