Don’t forget a ride on the top deck of a red double decker bus (take the number 15 from the east side of trafalgar square… down The Strand past St Pauls to the Monument or on a little further to the Tower…
I’m not sure going into the Tower is worth it.. (especially if you have been to science/NH museums before) but defo go down there to see it and tower bridge, the Belfast, the Shard (try and guess how tall it might finish up being, from the slopes of the side… In my mind it just keeps getting taller) and the other tall buildings of the City
Try the Duck bus… never been on it myself but looks great fun…
http://www.londonducktours.co.uk
Oh forgot to mention…. sight seeing is knackering, even when you know your way about…. might need to take that into account with the dustbin lids…. Science/NH is a day in itself…. Buck Palace, through St James park to Horse guards, onto trafalger, bus, tower back along river to westmister (good idea) is a nice loop and will again propbably take all day.