Booked the two day pass for myself and my husband at a cost of $120 and to be honest it was not worth the money. The audio guide was more music than talking and half the time it wasn’t in sync with the sites that you were passing. We had to move seats quite a few times because the headphone socket didn’t work for one of us, or when the bus was busy we had to share headphones in the one socket that worked.
We travelled on the Blue line to visit The Pentagon followed by Arlington Cemetary but the bus didn’t stop at the scheduled stop for The Pentagon, when I asked the tour guide he said ‘Oh we don’t stop there anymore, you’ve got an old map’, I then took a new map from the front of the bus and The Pentagon stop was on this one too! We ended up getting a subway outside Arlington back to The Pentagon and then a subway back to DC all at an extra cost.
If you are in DC and reasonably fit then most of the sites are within walking distance so I would say do this and use the subway, which is much cheaper, to get to the sites further away. I have used the Big Bus in many other major cities and it has always been good but the DC one was very disappointing.