We had a very poor experience with the Big Bus Tour. First, we got on, and the lower portion of the bus is completely unheated. It was a chilly day, and the reason for booking a bus tour, as opposed to walking, is so that we could warm up on the bus. Obviously I wouldn't expect the upper, open portion of the bus to be heated, but one would think that the enclosed lower portion would be heated.
Second, our guide talked so fast it was nearly impossible to understand him.
Third, they applied graphics to the exterior of the bus windows making it seem like you're looking through very dirty glass. Why would a bus tour company do that? it's ridiculous. None of the other bus tour companies appeared to do this.
And lastly, we missed our second bus of the morning because the driver literally stopped for 15 seconds before moving on to the next stop. The least they can do is have their drivers stop for a minute to give people a chance to find them and get on. Their stops do not have clear signage, so you're sort of waiting in a general "area" for their bus, and when you see the bus pull up, apparently you need to spring over to it.
At this point (after 1 stop) we decided it would be more enjoyable to just Uber from one landmark to the next. So we essentially paid $80 for 2 people to get on at the US Capitol and get off at the Spy Museum.
I would NOT suggest Big Bus Tours. Save your money and book elsewhere. Or just Uber/Lyft from location to location.