Washington D.C., District of Columbia
The transfer bus was easy to find but once found I was directed to re-enter the airport to get confirmation of travel. I then had to wait for a period of time before entering the van.
I have used the hop-on hop-off tours in many capitals around the world. These are a truly a great way to get around and see everything. In Toronto I could just hand my printed voucher to the attendant to gain my ticket for the multiply days. Would recommend this most highly.