Just some suggestions for everyone: The Castle has the "loot pile" exhibit from the movie Night at the Museum. Also American History Museum has just reopened after a few years of renovations. I recommended taking pictures in the sculpture garden...always a great place to take pictures of the group. Hope Diamond, dinosaurs and other great exhibits in Natural History Museum. Air and Space Museum is never disappointing if you enjoy airplanes and space travel. Use the website and click on the different museums to get some ideas of what you want to see. If you have any questions, let me know...I will try to help you out.
I know...it's tough to decide right now, but keep in mind you only have a little time. The museums are spread out; plus you have to go through security at each one. You will have to go with a game plan!