Go to the Eiffel Tower at night, and you'll probably never see anything as pretty again. Although, at this time of year the queues will be horrendous, and there's not much chance you'll get to go to the top level. Some of my favourite things are - the food market on Rue Mouffetard, sitting at the edges of the Ile de la Cité (where Notre-Dame is), and the restaurant 'Mollard' (near where you're staying, on rue Saint-Lazare) is so lovely and traditional you just never want to leave. If you have time, take the train out to the Versailles Palace. Be careful crossing Place Charles de Gaulle. Its awful.