A great place to start the day if you are in South London is Federation Coffee in Brixton Village. The food is great and so is the coffee. This is a very chilled place where you can get both and indoor and outdoor experience (even though the whole place is under the Village roof).
There are not many places in London like it. On a Saturday during market hours it heaves with stalls and visitors for a good mile or two. Great place to pick up some bric-a-brac, genuine oddities and a great bite to eat, or just enjoy the hustle and bustle vibe of the place.
Zédel is my absolute favorite restaurant in London. Beside the fact that I love french cuisine, Zédel is aesthetically pleasing, very reasonably priced, is good for any occasion, and of course - delicious. My favorite is the bouillabaisse and a bottle of the Bordeaux Superior.
I've had a love affair with the BT Tower for some time now. Unfortunately entrance to the public was shut in 1980, but earlier this year I was invited up to the top, where the revolving restaurant once stood. The views were absolutely breath taking.