First and foremost, London is a walking town. While they have some of the best public transportation in the world, to view London, you will do a lot of walking. You will never run out of beautiful architecture to photograph, and that's above and beyond the well known landmarks.
Pubs abound and the general attitude is very open and happy. The Brits understand, I think sometimes better than most, that life is life and you take it all with a grain of salt and a sense of humour.
If you want to see the "classic expected London" with it's statues, Big Ben, and monuments, most are within walking distance from the Thames. Take a short tube ride north the Camden Market and experience the funkier side of London with touristy t-shirts and anything else you may want as far as presents for friends and family back home.
I highly recommend the Europa Bed and Breakfast in Islington (Tuffnel Park tube stop). Their rates are excellent for the kind of rooms available and the included hot breakfast is a notch above most. Family owned and operated. Very nice people. Walking distance from the Europa B&B is a pub called The Swimmer... EXCELLENT FOOD and a definate hidden GEM.
Happy traveling if you are heading for London. I save up and go each spring and wouldn't miss a trip.