Then consider visiting the Wallace Collection's current exhibition, Portraits of Dogs: From Gainsborough to Hockney, on through mid-October. I spent close to two hours the other day going through the exhibit, which consists mainly of paintings but also has drawings and some sculpture. My favorite room showed David Hockney's portraits of his dachshunds Stanley and Boodgie. There's also a small room of photos of QEII with her corgis. After having something to eat in the light-filled cafe, I briefly walked around the remainder of the collection (I had somewhere else to be), which is full of gorgeous things.
All in all, a very pleasant morning/early afternoon out.