Caiti asks for some suggestions of what to do in London. Let's see what suggestions I can make. 
First of all, don't take tourist buses. They're extremely expensive compared to taking the normal buses. One of the best ways of seeing London is to grab yourself a bus pass (or Oyster card) and just ride around everywhere. London buses have all the failings of bus services - they're slow, often late and often stop unexpectedly. That said, they are easy enough to understand. They are well-described on the TfL website and the Journey Planner.
Some places and things, then.
Speakers' Corner. If you are ever in London on a Sunday morning, take some time to go up to Speakers' Corner in Hyde Park. The closest tube station is Marble Arch on the Central line. You may even find me there, keeping alive the tradition that has been part of London spanning through both Karl Marx and George Orwell.
An old Routemaster bus. A lot of people have a lot of nostalgia for Routemaster buses. I'm not as nostalgic as some other people are about them, but they are still fun to ride when you can find them. They do run on certain routes - number 9, for instance - but for shorter distances (number 9 only runs to the Royal Albert Hall instead of all the way to Fulham). If you want to take one, go to Aldwych or Charing Cross station bus stops and wait. You may be there for a while, but one will turn up. Buy a ticket, get on and sit down. The ticket attendant will pop over shortly and check your ticket. To get the full experience, you've gotta sit upstairs at the front.
Go in to St. Paul's. It's one of the most magnificent places of worship in London.
Make sure you go to Foyles in Charing Cross Road. It really is one of the best new bookshop in the world (Baggins in Rochester, Kent is the best second-hand bookshop - at least in the UK).
Hop on to Upcoming and find something of interest on there.
I'll post some more later, but if you've got ideas for Caiti, feel free to drop them in the comments.
