All the tips on here are GREAT! Thank you to all the posters. But I have noticed that there are tons of great 2 for 1 admissions to places of interest if you come into London from out of town via the rail. Seems that if we stay in town, the same deal is not available. It starts to get all kinds of complicated with buying an Oyster card but also buying a paper rail tickets, but using it only to get 2 for 1 tickets... help! help! help! So confusing. Am I correct in believing that if we stay in town to be near to things and avoid lots of traveling, we will be left out of great twofers?