I second the suggestions for stores on Oxford St., Liberty on Regent St. (an unusual store and very interesting building),New Bond St., Cabinet War Rooms....you can walk through St. James Park and come out right near the entrance.... also Westminster Abbey( stay for evensong, a lovely experience). And I would add Hampton Court Palace as a day trip....trains leave regularly from Waterloo Station (about 45 minute ride) and you're there within walking distance. You could easily spend all day there. If you want to see more silver in one place than you've ever seen in your life, try the Silver Vaults in Chancery Lane....very interesting part of London as well and near St. Paul's. Have a great trip! Even though security problems have sprung up, you'll have a wonderful time.