thread natural history museaum
madame tussades,
the london dungeon

or the john soane museum is nice
a wander round borough market
go up st pauls, or the orbit, or the sky garden of cocktails at duck and waffle.

or a go on the dangleway

open top tour
permalink st paul's is a good idea
we did the science museum a few years ago, that was excitingly shoddy.
permalink the zoo is also good of course

the V&A is also worth a look.

or go to the pub
permalink I was thinking zoo (see above)
because if the weather was nice the park would be fun potentially. Madame Tussauds would just be creepy.