You must see a lot of things in London. But in time, you get tired of the crowds of tourists and the heat (it was over 90 degrees in London in June!) then take yourself and your family to Kew Gardens. It is reachable by Tube (Richmond train on the District Line) and you are immediately immersed in GREEN. Beautiful gardens, flowers, trees, ponds, period buildings, etc. Go the Kew Palace while there. Go inside the tropical hot house. In short, spend the morning or afternoon just wandering and recharging those green cells. Worth a visit, not just a detour.