Everyone is of course different in their likes and limitations. The Weekend Warrior suites me. The trains are cheaper on the weekend off peak rates. The tubes and buses are nearly empty on Sunday morning and it is a great time to get around town, grab some breakfast, stroll in the park and blissfully wander around taking photos and absorbing the essence of one the world's truly great cities.
Harrod's - The world's best shopping experience.
House of Parliament - Go inside - Don't miss it and its free.
Knightsbridge - English Elegance