The tourist pass for sightseeing in London
The London Pass allows to visit most of the attractions of London, with the same mechanism of the buffet. You pay for the ticket at the beginning and after that all the included attractions can be viewed without any additional cost and without the normal queues at the entrances to buy tickets.
The optional London Pass travelcard in addition allows to use public transports to visit London during the validity of the pass.
The fact that the owners of the pass can save time for avoiding the queues is very useful particularly in peak times like holidays and weekends.
The pass can be bought directly before leaving, solving from the beginning all the issues with transportation inside London.
For more information about the pass it is useful to see this external page about the London Pass.
New York Pass. Not only in London is possible to get this tourist pass but in New York too, and there too it includes a transport option on double decker tourist buses. Read more about the New York Pass with transport.