The many book stores dotted along this strip can provide hours of inspiration. Aside from those selling new books, several specialise in second-hand and antiquarian books.
I grew up in Brighton which is full of cheesy bars like this. If you can handle being surrounded by multiple screens playing Kylie at full volume, its pretty much the cheapest bar in central london. The cliental is so varied its great for people watching and completely un pretentious.
I spent a lot of time in the British Museum whilst studying for my Degree. My work has changed considerably since then but it is still a place I return to again and again. Inspiration doesn't always come from objects in the collection but also from the space and its visitors.
Even if you have seen it hundreds of times it will still stop you in your tracks. A great piece of architecture and apparently the largest brick structure in Europe.