Nick was our guide and Thomas our driver. Both were terrific. Nick loves telling stories and is v theatrical in how he presents the information about Washington. The tour is a combination of drive by, hop off and walk around. You visit most of the major monuments - well in the case of Capitol Hill - it is a stop and photo opportunity. But separately you can join one of the free tours of this site which we did via our hotel. If you were trying to do this in the busier seasons I would definitely recommend booking ahead.
The Tour also took us to the White House, WWII, Martin Luther King, Abraham Lincoln, Thomas Jefferson, Korean War, Vietnam War memorials - we stopped at all of these and had plenty of time to look around, take photos etc.
We did not see or stop at Georgetown, The Smithsonian or Arlington Cemetery. These sights you need to do on your own.
Tour finishes at the National Archives building which means you can see 1 of 4 copies in existence of the Magna Carta, original copy of the Declaration of Independence and Bill of Rights. All pretty cool.
The tour is pretty full 9-4 although we finished early as we were only a small group. Definitely recommend it.