I think we had the best tour guide possible. He had a great sense of humor and knew an amazing amount of detail. He encouraged questions and answered them fully and graciously. He was careful about the physical limitations of some of us, but also would not hold up the tour for those few who ignored the agreed-upon back-at-the-bus rendezvous time.
It was just OK. The 6-hour trip was not worth it more than the 3-hour. The 3-hour and 6-hour made it a large group traveled together until the 3-hour people left. The tour guide didn't engage the people enough.
Outstanding 6 hour tour of the nations capital! The guide was fantastic! Knowledgeable, enthusiastic, excellent communicator. Saw and learned so much in a one day tour! Would highly recommend, especially if you have never been to DC before. Do it early in your trip. They will give you many ideas of where to go from there!