I should have known better than to book tour bus on a holiday weekend. Too many streets were closed, so not all the stops could be made. This was just bad luck, nothing the company could do.
I had far better luck when I tried a different company on a different day.
The reason I tried a different company, rather than using Big Bus again, was that the staff seemed harried, and the graphics over the windows kept me from being able to get any good photos. Then, in 90+ degree heat, we were moved from an air-conditioned bus to a non air-conditioned bus with no explanation given. I walk with a cane and needed assistance with the high steps on and off the bus; other passengers helped me because the staff never offered even though they saw me.