This tour is great! Our guide, Corey, was very knowledgeable and fit in time for us to see the Air Force memorial and 9/11 memorial. We loved that we were able to get out and walk around to get pictures at each stop. An air conditioned van and the provided cold water was great on the hot day of our tour. Highly recommend this tour! 4 hours was the perfect amount of time, stops at almost all of the major sites, and had 10-20mins at each stop to explore.