Not a great weekend to be in London and slightly dazed - drizzly and rather depressing everywhere.
I have some American friends over at the moment (ferrying them out to Heathrow this evening) but if you're bored on Sunday and want to meet up for a beer just post here and I'm sure you'll find some takers.
If my American friends are good judges then the best tourist thing to do (aside from the museums - and the National Portrait Gallery is free and bang in the middle of the tourist area between Trafalgar Square and Leicester Square) is The Tower of London. Sounds
like this was the highlight of their whole trip which included 2 weeks in Paris.