In DC. The highlight of my trip, was the Library of Congress. Had to get free tour tickets, through my Senator. Almost skipped it, because..... I thought it was just a library. I was in awe. The paintings directly painted on the walls. The carved delicate marble, everywhere. The dome ceiling, showing the history of our nation, I could have looked at it for an hour, and not seen everything. The stories that the tour guide told, about the building of the Library.
Probably have to take Subway, don't know about parking places. Ask the Senators office. They can tell you.
You will have to call your Senator, and give SS#"s and birthdates, and Drivers Licence copies through fax. You may be able to get tickets. Don't think you have a chance, at this late date, to get tickets to the WhiteHouse, or Senate. Those go very fast, and long waiting period.
You could go to where they print the money, but you have to get there at 7:00 am?? and get timed tickets for the rest of the day. We got there at 8:30 am 2 days in a row, and they were out for the whole day. If you want me to give you directions to where you stand in line, I can tell you. Just PM me.
Arlington cemetary closes earlier than I would have thought. Since you will have a car, there is parking, you can cut off a long walk from the Subway to the cemetary. I would check online, to see closing time. Definately worth watching the changing of the guard at the unknown soldier.