Torn between the more affordable Bus Tours and the "over our budget" Black Cab tours. Leaning towards bus ... only concern is that the lines will be so long at different sites that it will shorten our time to enjoy (rope bridge, for example). I also understand that on "cruise ship" days there are literally thousands of people vying for places in line, etc. Like the idea of being with a bunch of people from different places on a bus for one day. Any advice on which way to go?