Come to South Kensington. I can give you a VIP tour of the Natural History Museum, including some of the behind-the-scenes stuff, and you've got the science museum and V&A museum across the road. Harrods is a 5 minute walk away and if you fancy a nice afternoon tea, the Royal Albert Hall does a really good one for decent money too. Then you've got Hyde Park up the road where you can rent bicycles and have a nice little pootle to Oxford Street if you fancy it.