Tourmobile is great, but the seats stink if you have long legs. They are Sooo crammed in together. And a lot depends on who the person doing the announcements is. There are some really good ones, really bad ones, and lots of in-betweens.
You can see the Washington Monument, World War II memorial (kinda stinks), the Reflecting Pool, the Lincoln Memorial, and the Koren War thing all in one swoop, they are all in there together. And the White House is within walking distance of them, too. You can't tour the White House or even drive by anymore, you have to walk and take pictures through the black, iron fence thingy. You might wanna prepare the kids for the goofballs who hang out in front (or behind? I never can remember which is the front) of the White House. There are always people there protesting or standing up for something, and they get a little silly about it.
I like the Smithsonian museums, too.
If you plan on visiting the Holocaust Museum, do it last or on a day you have nothing else to do. It is, by its nature, very depressing.