During my last visit to London in 1996, Covent Garden was my favorite spot to hang out.
There's a rather sweet Doc Marten store near there, for one thing. I had never seen one of those before.
There's also a rather fascinating number of bazar style outdoor shops, various resturaunts, and a number of theatres.
Not to mention some great outdoor entertainment. You never know when you're going to see some sort of busker, juggler, or varied entertainer there.